Paul Markwick

Faults and folds are amongst the clearest expressions of past tectonics that we can observe directly.

The graphical representation of these features depends on application and scale.

On geological maps, structural elements are usually shown by lines. These mark the trace of the intersection of each structural feature with the Earth’s surface. Kinematics are represented graphically by a commonly applied symbology (Figure 1). In many structural maps, sub-surface features are also represented by extending their top trace vertically until it intersects the current land surface (in our databases, we use an attribute to distinguish between features exposed at the surface and those in the sub-surface). This combination of line features is what John and I had in mind, given our focus on New Ventures exploration and how we would use the framework: to define the crustal architecture, build tectonic models and then develop paleogeographies.
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When we get to prospect scale (Figure 2), it becomes essential to consider the 3D geometry to calculate volumetrics, investigate fault closure, trapping mechanisms, migration pathways, etc. To this end, we build structural contour maps and show our faults at the surface as polygons representing the dip and throw of each fault plane with depth. 

This difference due to application and scale is nothing new. It was also not the cause of the problems that John and I faced.

I have been thinking about this recently. Primarily because I am once again building a global crustal architecture geospatial database, this time armed with 30 years of experience, much older and hopefully a little wiser. But also, because I am writing a new paper on the history of geological representation.

Much has changed since 2004. For example, our understanding of the complexity of crustal architecture has developed substantially in the last decade due to the increased availability of ultra-deep, 2D seismic data along many of the world’s continental margins (Manatschal, Sutra and Péron-Pinvidic, 2010; Péron-Pinvidic and Manatschal, 2009). Databases and map representations need to take account of these advances.

The new databases I am working on are more systematic, more integrated, more detailed, and based on more data. The workflow begins with the Structural Elements database, forming the framework around which all the other elements are built. Hence the reference to a structural ‘framework’. So, getting this database right, or as correct as possible, is critical because everything else hangs from this. Everything from the crustal facies and geodynamics databases to how we define our sedimentary basins and their depositional fill, and ultimately to plate reconstructions, paleogeography, and paleolandscapes.

In revisiting this whole process and detailing the mapping workflow, I realized that some questions need to be explicitly addressed from the outset if we are to get others, not least our staff, to know what we want. These questions include the following:

1. Should the maps be based on map interpretations published by other people (secondary data) or interpreted from primary data?
2. Should we assume that existing interpretations are correct?
3. What density of structures should be mapped?
4. Should only features with a direct link to petroleum be recorded?
5. Should the maps only show the present-day geometry of features or show the past geometry at a time of the compilers' choosing/interest?
6. Should the maps be schematic with segments linked into a continuous form (general pattern of faults and folds) or only what is ‘observed’ (actual or as close to reality as possible)?

The answers to these are relatively straightforward once stated (answers at the end of the article) – operationally, these are now addressed in the extensive documentation created for each database.

In this blog, I want to look at the history of structural mapping as a way to try and explain the problems that John and I encountered. Because by looking at this history, we can hopefully get closer to answering the fundamental question: What is a structural map? 

When Thomas Sterry Hunt first described the process of making his paleogeographic maps in his 1873 paper (Hunt, 1873), he stressed the importance of first understanding the underlying “architecture [of the Earth]”
“The structure and arrangement of the materials of the earth’s crust, its architecture, as it were…”

In this, Hunt was likely influenced by his experience as an exploration geologist and how structure often dictated the distribution of oil – Hunt was one of the first to recognize the link between anticlinal structures and oil fields (Hunt, 1862).

Crustal ‘architecture’ is much more than mapping the structural ‘framework’ as a structural elements database. It encompasses all the crust. In reading back through the early 19th century literature, it is clear that when geologists referred to ‘structure’, they were using it in the same way as Hunt used [crustal] “architecture”. Indeed mapping faults and fold axes as lines developed relatively late in geology.

Folding and faulting showed how dynamic the Earth was. You only have to read Humboldt, Hutton, or Lyell to get a sense of this. But when these geologists came to map this deformation, the resulting ‘structure’ was defined by outcrop geometry in map view or bed orientation in sections, rather than by discrete fault lines and planes. The maps of Smith, for example, show outcrop geometries that define folds and faulted boundaries but do not show the fold axes or faults themselves. Similarly, his cross-sections.
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So in this 19th-century view of a ‘structural map,’ we are not just representing the trace of fold axes or faults but the entire 3-dimensional crustal form. In terms of the databases I am building today, this would require three separate but related databases: (1) structural elements, which define the three-dimensional geometry of the rock volume, including folds and faults as a framework of line traces; (2) 'crustal' facies describing the geometry and composition/rheology of the lithosphere; and (3) bedrock geology, comprising the surface outcrop. We might add (4) igneous features; and (5) geodynamics, representing the dominant thermo-mechanical processes acting on the lithosphere. Both of these give additional information on the dynamic processes that generate the form.

​It was Henry De La Beche who explicitly showed faults as lines in his sections (De la Beche, 1830). These thick black lines in sections (Fig.3) were replaced in map view by thick white lines. This symbology continued to be used on British maps throughout the 19th century (Fig. 4). There was no differentiation between different types of faults.

But a search of 19th century maps suggests that the inclusion of fault traces was not universal. Even Élisee Reclus in his seminal work on global geography, did not show maps of major fault lines, although he did provide maps of the East African rift, showing the topographic fault scarps (“Line of Volcanic Fault” (Fig.104 in Reclus, 1876). 

The most significant change in structural mapping occurred in the 1880s, when John Wesley Powell, the second director of the newly formed USGS, started a drive to standardize map symbology and colors. In these maps, Powell explicitly showed structural elements (Powell, 1882), but like De la Beche, these were heavy black lines without associated markers. Powell also used dashed lines to show fault extents where the trace could not be discerned but was assumed to continue. Forty years earlier, De la Beche had also shown dashed fault lines on some of his maps, but had not explained what these meant in the legend; one assumes to show uncertainty like Powell:

“Fault lines (particularly when they are formation boundaries) shall be indicated when actually traced by somewhat heavy full lines in black; and when not actually traced, by similar broken lines, toward which the formation devices may blend or fade as circumstances seem to require.”
(Powell, 1890)

This standardized approach to mapping was implemented under the auspices of the next USGS Director, Charles Doolittle Walcott.  The results can be seen in the USGS “Folios of the Geologic Atlas of the United States”, a series published between 1894 and 1945, which included maps of topography and geology with an emphasis on structure and economic geology (see Figure 5 for an example from the Little Belt Mountains in Montana; Weed, 1899).  Some of these folios also included structural contours on the maps (see Figure 6 from Clapp, 1907).

​The folios of Walcott during at the turn of the 19th-20th centuries look remarkable modern. But this ‘standard’ symbology does not seem to have been systematically adopted more widely outside of the U.S.. The British Geological Survey continued to mostly use white lines to represent faults until around 1912, after which they were changed to darker colors such as dark browns (Fowler et al., 1926) or dark blue lines (Ussher and De la Beche, 1953) (Figure 7). Although Strahan’s geological map of Ingleborough in 1910 (Strahan, 1910) users black lines and is more similar to Powell's scheme and the USGS folios.

​The nomenclature of Powell was expanded in 1920, when the USGS published formal guidance to its geologists on how to prepare illustrations and maps (Ridgway, 1920). Faults on maps were now represented by lines with associated marker symbols to indicate the footwall and hanging wall sides of normal faults, and overthrust (upper plate) side of thrusts. Anticlines and synclines were represented by a line along the fold axis, differentiated by arrows perpendicular to the line - a symbology that has changed little since (Figure 8).

​This map nomenclature was quickly adopted and most clearly exemplified in the detailed local USGS maps of the time, for example, the excellent 1929 geological map of the Tyrone quadrangle in Pennsylvania (Figure 9) in which thrust faults, normal faults, synclines, and anticlines were differentiated (Butts, 1929). In Britain, the 1:63,360 map of Norham used a tick mark to denote the downthrown side of faults (Fowler et al., 1926). But we can also see its use in exploration maps during the following decades (Figure 10). And it was the oil Industry that then started to drive the need for more significant differentiation in the structural elements symbol set. 

It was becoming clear that there was a much greater diversity of structural models – different fold and fault types - that needed to be represented graphically (Boyer and Muehlberger, 1960; Crowell, 1959; Davis, 1913; Hill, 1947; Hubbert, 1927; Reid et al., 1913; Sopwith, 1875; Straley III, 1934).
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In 1950 the USGS expanded the range of recommended fold and fault symbols (Cloos et al., 1950),  including many that we still use today. But it still lacked the diversity of symbols that we use today. It also restricted some symbols to specific types of maps (Figure 11). 

​From 1989 to 1995, the USGS built a more extensive cartographic standard map symbol (Reynolds, Queen and Taylor, 1995; Soller, 1996). In this version, all thrust faults were represented using the saw-tooth marker pattern, which is now the most widely used visualization. Normal faults were still represented by a tick mark to indicate the downthrown side.  This was further expanded with the 2006 update to the USGS symbol set (Federal Geographic Data Committee, 2006). However, confusingly here, the USGS chose to represent normal faults with half-circles indicating the downthrown side and rectangles to represent the upthrown block of reverse faults. Unfortunately, by this time, other structural geologists and many companies had already appropriated the idea of using rectangle markers but to replace the tick marks on normal faults (Hulshof, 2012; Markwick, 2019); this included Robertson Research in the late 1990s, which is where I got into the habit. Other organizations, such as the BGS, continue to use tick marks (Mawer, 2002).
 
With this diversity of map symbols, we can create a more detailed map of the ‘structural framework’ built of structural elements. These are the map representations of the structure rather than the whole structural form: a fold axis, not the entire fold form, a fault trace at the surface (or top sub-surface fault trace), not the whole fault plane. It is these elements that are recorded in our Structural Elements database.
 
This distinction may seem like semantics. But it is important, and as we stressed at the beginning of this article, it is a function of the application. In New Ventures exploration or plate modeling or paleogeography, we need to understand the overall structural context and what it tells us about geodynamic evolution, whether for basins or basin hinterland. But at the prospect scale, we need to understand the form.
 
This explains why we distinguish between the “structural framework” and the “crustal architecture” of which the framework is an integral part in our paleogeographic workflow.
A further complication here is that when we talk about ‘crustal’ architecture, we are, of course, referring to the whole lithosphere - nothing is ever simple!

So, what was the cause of the problems that John and I had?

In truth, even with 15 years of hindsight, I still do not fully understand the causes. But I think I have more of an idea than I did then.

What is a structural map? When looking at the example in figure 1, everything seems obvious. John and I had assumed that all structural geologists saw a structural map, in the same way, especially the most experienced structural geologists, those with the most years. But what they ‘knew’ and we ‘knew’ turned out not to be the same.

In our defense, I should point out that we ultimately hired a brilliant Polish structural geologist, whose tectonic model of SE Asia is, I still think, one of the best solutions I have seen for that area. And then a series of excellent MSc graduates who all immediately understood what we meant. So perhaps it was also partly the individuals concerned after all? Perhaps…
 
Structural mapping is fundamental to solving geological problems, especially in resource exploration. Getting the structural framework right impacts everything else, which we then build upon it.

As geologists, we all ‘know’ what a structural map is. But what we ‘know’ has changed through time,  depends on the application, and, as it turns out, it may also depend on the geologist you ask.
So what have I learned? Always explicitly define what you mean and assume nothing. 

If you would like to learn more about the Knowing Earth suite of structural and crustal architecture databases or any of our other Knowing Earth databases, please contact me at paul.markwick@knowing.earth.

This blog is part of a longer paper on the history of structural mapping that will be presented later this year.

The first version of the cartographic symbol set used by Knowing Earth was published as part of Markwick (2019) and is available through the Geological Magazine website https://www.cambridge.org/core/journals/geological-magazine/article/abs/palaeogeography-in-exploration/444CC2544340A699A01539A2D4C6E92A

The associated ArcGIS style file can be downloaded from my research website: www.palaeogeography.net

We will be publishing our new 2021 version shortly.

Others symbol sets available on-line.
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USGS: https://ngmdb.usgs.gov/fgdc_gds/geolsymstd/download.php
BGS: http://nora.nerc.ac.uk/id/eprint/3221/1/RR01001.pdf
Shell: https://www.arcgis.com/home/item.html?id=8a89e7ffe4154efa94c65090c4dab485
Knowing Earth: http://www.palaeogeography.net/publications.html

Boyer, R. E. & Muehlberger, W. R. 1960. Seperation versus slip. AAPG Bulletin 44, 1938-39.

Butts, C. 1929. Geologic map of the Tyrone quadrangle, Pa. Harrisburg, Pa.: Pennsylvania Bureau of Topographic and Geologic Survey.

Clapp, F. G. 1907. 144. Amity folio, Pennsylvania. In Folios of the Geologic Atlas: USGS.

Cloos, E., Pusey, L. B., Rubey, W. W. & Goddard, E. N. 1950. New list of map symbols: [for use in publications of the Geological Survey]. p. 6. Washington, D.C.: United States Geological Survey.

Crowell, J. C. 1959. Problems of fault nomenclature. Bulletin of the American Association of Petroleum Geologists 43 (11), 2653-74.​

Davis, W. M. 1913. Nomenclature of surface forms on faulted structures. GSA Bulletin 24 (1), 187-216.

De la Beche, H. T. 1830. Sections & views, illustrative of geological phaenomena. London: Treuttel & Würtz, 71 pp.

De la Beche, H. T. 1845. 1:63,360 geological map series [Old Series] Sheet 19, [Bath, Frome, Axbridge, Wells, Glastonbury, Bruton, Mere, Somerset Coalfield, and southern part of Bristol Coalfield.] , Solid. Geological Survey of England and Wales.

Federal Geographic Data Committee 2006. FGDC digital cartographic standard for geologic map symbolization. p. 290. Reston, VA.: Prepared for the Federal Geographic Data Committee by the U.S. Geological Survey.

Fowler, A., Carruthers, R. G., Geikie, A. & Gunn, W. 1926. 1:63,360 geological map series [New Series] Sheet 1, Norham, Drift. Revised. Geological Survey of England and Wales.

Hill, M. L. 1947. Classification of Faults. AAPG Bulletin 31 (9), 1669-73.

Hubbert, M. K. 1927. A suggestion for the simplifcation of fault descriptions. The Journal of Geology 35 (3), 264–69.

Hulshof, B. 2012. Shell Standard Legend. p. 38. Amsterdam: Shell Global Solutions International B.V.

Hunt, T. S. 1862. Notes on the history of petroleum or rock oil. In Annual report of the board of regents of the Smithsonian Institution, showing the operations, expenditures, and condition of the institution for the year 1861 pp. 319-29. Washington, D.C.: Government Printing Office.

Hunt, T. S. 1873. The paleogeography of the North-American continent. Journal of the American Geographical Society of New York 4, 416-31.

Jenkins, O. P. 1943. Geologic formations and economic development of the oil and gas fields of California (In Four Parts, Including Outline Geologic Map Showing Oil and Gas Fields and Drilled Areas). In California Department of Natural Resources, Division of Mines, Bulletin p. 773. California Department of Natural Resources, Division of Mines.

Manatschal, G., Sutra, E. & Péron-Pinvidic, G. 2010. The lesson from the Iberia-Newfoundland rifted margins: how applicable is it to other rifted margins? In Central & North Atlantic Conjugate Margins Conference Lisbon.

Markwick, P. J. 2019. Palaeogeography in exploration. Geological Magazine (London) 156 (2), 366-407.

Mawer, C. H. 2002. Cartographic standard geological symbol index, Version 3. p. 49. Keyworth, Nottingham: British Geological Survey.

Péron-Pinvidic, G. & Manatschal, G. 2009. The final rifting evolution at deep magma-poor passive margins from Iberia-Newfoundland: a new point of view. International Journal of Earth Sciences (Geologische Rundsch) 98 (7), 1581-97.

Powell, J. W. 1882. Second Annual report of the United States Geological Survey to the Secretary of the Interior, 1880-1881. In Annual Report p. 764. United States Geological Survey.

Powell, J. W. 1890. Tenth Annual report of the United States Geological Survey to the Secretary of the Interior, Part 1: 1888-1889. In Annual Report p. 774. United States Geological Survey.

Reclus, É. 1876. The universal geography : the earth and its inhabitants. vol. XIII. South and East Africa. London: J.S. Virtue & Co., Limited, pp.

Reid, H. F., Davis, W. M., Lawson, A. C. & Ransome, F. L. 1913. Report of the committee on the nomenclature of faults. GSA Bulletin 24 (1), 163-86.

Reynolds, M. W., Queen, J. E. & Taylor, R. B. 1995. Cartographic and digital standard for geologic map information. In USGS Open-File Report p. 257. USGS.

Ridgway, J. L. 1920. The preparation of illustrations for reports of the United States Geological survey : with brief descriptions of processes of reproduction. p. 101. Washington, D.C.: United States Geological Survey.

Soller, D. R. 1996. Review of USGS Open-file Report 95-525 ("Cartographic and digital standard for geologic map information") and plans for development of Federal draft standards for geologic map information. In USGS Open-File Report p. 12. U.S. Geological Survey.

Sopwith, T. 1875. Description of a Series of Elementary Geological Models Illustrating the Nature of Stratification ... with Notes on the Construction of Large Geological Models. R.J. Mitchell & Sons, 82 pp.

Strahan, A. 1910. Guide to the Geological Model of Ingleborough and District. pp.

Straley III, H. W. 1934. Some notes on the nomenclature of faults. The Journal of Geology 42 (7), 756-63.

Ussher, W. A. E. & De la Beche, H. T. 1912. 1:63,360 geological map series [New Series] Sheet 350, Torquay, Drift. With additions. Geological Survey of England and Wales.

Ussher, W. A. E. & De la Beche, H. T. 1953. 1:63,360 geological map series [New Series] Sheet 350, Torquay, Drift. With additions. Reprint. Geological Survey of England and Wales.

Weed, W. H. 1899. 56. Little Belt Mountains folio, Montana. In Folios of the Geologic Atlas: USGS.

Q1. Should the maps be based on published maps (secondary data) or interpreted from primary data?
 
Answer. The intention is that all structural features in the database should be identified in primary data. This data includes gravity and magnetic data, seismic, radar, bathymetry, topography, Landsat, and observations. Features from secondary (published) data are only included if the feature is considered important but cannot be seen with primary data available (remember that the primary data are all publicly available). In these cases, the feature will carry by default a low mapping confidence and will have attribution reflecting its source. We have kept such ‘secondary’ interpretations to a minimum (<<1% of the entire database).
 
Q2. Should we assume that existing interpretations are correct?
 
Answer. Assume nothing. Generally, the location of a feature would have been placed using primary data and information from published, secondary sources will refer to the age assignments or kinematic histories. Attribution is used in the database to explain the source of this information – i.e., what it is based on if quoted in a paper.
 
 
Q3. What density of structures should be mapped?
 
Answer. This will depend on the data grain and structural complexity. Map what you can see, but consider a set resolution limit and keep to that. This becomes the “minimum resolvable feature” in the database. In operation, there is a clear density difference between features mapped on land using Landsat or SRTM3 radar data and features in the oceans constrained only by satellite-derived gravity anomalies.
 
 
Q4. Should only features with a direct link to petroleum be recorded?
 
Answer. No. This database is about understanding the Earth so not restricted to any single application.
 
 
Q5. Should the maps only show the present-day geometry of features or show the past geometry at a time of the compilers' choosing/interest?
 
Answer. The default database is the present-day geometry. Separate databases are used for each geological timeslice starting with features extracted from the present-day database and rotated. Changes in kinematics are stored in a related “Activation” table. Also, be aware that there will be cases where features will need to be spatially adjusted after rotation to reflect deformation (palinspastic reconstruction), especially in compressional settings. In the oceans, there may also be features that no longer exist (subducted).
 
 
Q6. Should the maps be schematic with segments linked into a continuous form (general pattern of faults and folds) or only what is ‘observed’ (actual or as close to reality as possible)?
 
Answer. Observed takes precedence, but connections may sometimes be useful. If so, connections will have the lowest confidence and be dashed. This is why attribution is so crucial.

A pdf version of this blog is available for download here

In the age of AI (Artificial Intelligence) and machine learning, there is a temptation to assume that all we need to do is to ‘train’ our software, load in the data, and wait for the answer.

“42” instantly comes to mind - for those of you old enough to remember the prescient imagination of Douglas Adams and “The Hitchhikers Guide to the Universe”.
There is no question that both AI and machine learning have a huge potential in helping us better understand the world. Computers provide us with the capability to interrogate the vastness of our data libraries and to draw out patterns and conclusions that we would otherwise not have the time to do. The developments in these techniques are impressive. If you are not convinced check out the Google AI site (https://ai.google/).

But we need to be careful.

Not because AI is not useful, it is. But because there are fundamental issues around data and analytics that we must answer first:

1. Are we clear about the question(s) we are asking of our data and software? (Douglas Adams’ premise in Hitch-hikers).
2. Will we be able to understand the answers when we get them?
3. Do we trust our data?

Each merits an essay in its own right.
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Here, I am going to focus on the third – do we trust our data?

I have spent much of my career designing, building, populating, managing, and analyzing ‘big data’. From using paleobiological observations to investigate global extinction and biodiversity, to testing climate model experiments, to paleogeography, and petroleum and minerals exploration.

Having worked at each stage from data collection to data analytics I have gained a unique insight into data, especially big data.

Most databases are built to address specific problems, and no surprise, these rarely give us insights beyond the questions originally asked.

But when we think of Big Data and AI we are usually thinking of large, diverse datasets with which to explore, to look for patterns and relationships we did not anticipate.

My interest has always been in building these sorts of large, diverse ‘exploratory’ databases following in the footsteps of some great mentors I was privileged to have at The University of Chicago, the late Jack Sepkoski, and my Ph.D. advisor Fred Ziegler.

‘Exploratory’ databases have their own inherent challenges, not least the need to ensure that they include information that can address questions that the author has not yet thought of… That is a major problem.

This requires specific design considerations, especially, as I argue you here, the fundamental importance of ensuring that we know the source and quality of the data we are using. Because it is upon these data that we base our interpretations, and from those interpretations the understanding and insights we derive.

If the data are flawed then everything we do with that data is similarly flawed and we have wasted our time.

This is even more important when we are analyzing 3rd party databases that we have not built ourselves. How far can we, should we trust them?
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In short, we can have the best AI system in the world and the most powerful computers, but if the data we feed the system is rubbish, then all we will get out is rubbish.

In discussing data and databases it has become de rigueur to quote Conan Doyle: “Data, data, data! I cannot make bricks without clay!” Good old Sherlock, a quote for every occasion… ("The Adventure of the Copper Beeches" Sir Arthur Conan Doyle, 1892)

But what do we mean by “data”? 

When I started to write this article, I thought I knew.

But in looking through the literature I soon realized that such terms as “data”, “Big data” and “information” were vaguely defined and used interchangeably.

So, to help anyone else in the same position here is a quick look at the terminology, including some that you may or may not be familiar with. This is summarised in figure 1. A more comprehensive set of definitions is provided as supplementary data in the pdf version of this blog article.

The fundamental progression here is from data to verified data to knowledge, understanding, and insight (see the recent Linkedin article by the branding company LittleBigFish). 

Admittedly, in many ways trying to define the relationships between observations, facts, data and information is semantics.

For databasing we can reduce this to data and verified data, and this takes us back to the need to audit and qualify our data: the data to verified data transition.

When designing and building a database we need to ensure that we include information about the data.

For spatial geological data, we need to answer a range of questions about the data, including the following:

• What is the provenance of the data?
• What is the resolution of the data?
• What is the type of data?
• What is the data grain?
• What is the spatial and temporal accuracy?
• What is the spatial and temporal precision?
• What is the analytical technique used?
• What is the analytic error?
• If an interpretation what is it based on and why?

(For further information on this see Markwick & Lupia (2002)

Providing the answers to these questions will enable anyone using the database to replicate what was done and to make decisions on how they use the data.

Where this applies to the database as a whole it will be recorded within the metadata. The metadata also provides information on the intrinsic characteristics of the data in a database, such as data type, field size, date created, etc.

This is different from extrinsic information, such as the input data used for a specific database record. This extrinsic, record specific information is stored within the data tables themselves. For example, in our Structural Elements Database (see figure 3 attribute table), features may be based on an interpretation of one of several primary datasets, including Landsat imagery, radar data, gravity, magnetics, and seismic. This needs to be recorded because each primary dataset will have its inherent resolution and errors.

I have always believed that more explanation is required. So, within my own commercial and research databases, I have added text fields for each major inputs to describe the basis of each interpretation. For example, an “Explanation” field provides a place for describing exactly how a spatial feature was defined.
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All records are then linked to a reference library through unique identifiers (Markwick, 1996; Markwick and Lupia, 2002). This is a relatively standard design. (Nb. In my research, I use the Endnote software, which I have used since my Ph.D. days in Chicago in the 1990s and which I can highly recommend https://endnote.com/)

The problem for database design is knowing what level of auditing is needed to adequately qualify an individual record. This will depend on whether the record is of a primary observation – analytical, field measurement, etc – or an interpretation.

Interpretations can change with time. For example, a biostratigraphic zonation used 30 years ago may not be valid today, but the primary observations of which organisms are present may still be true (accepting that taxonomic assignments may also change). So in a database of this information, you would need to record not just the zonation (interpretation), but also what it was based on – this might either be a complete list of the organisms present (the approach I took with my Ph.D. databases) or simply a link to the reference which contains that information.

Another example that has driven me to frustration over the years is the use of biomarkers in organic geochemistry. Interpretations of these have changed frequently over the last 40 years. For example, the significance of gammacerane (the gammacerane index) which I remember in the 1980s as an indicator of salinity (Philp and Lewis, 1987), but which may (also) indicate water stratification (Damsté et al., 1995), or water stratification resulting from hypersalinity (Peters, Walters and Moldowan, 2007), or none of the above.

In both of these examples, we have an analytic error – misidentification of a species down a microscope or errors associated with gas chromography (GC), or GC-mass spectrometry (MS), etc – and an error or uncertainty in the interpretation.

In any database, we, therefore, need first to ensure that we differentiate between the two: observation and interpretation. We then need to record auditing information that covers both: what the biomarker is (observation); the analytic error in the observation; the interpretation; a reference to who made the interpretation, when, and why.  To which we can add a comments field and a semi-quantitative confidence assignment by the person entering the data into the database (see below).

By recording the reference of the interpretation and analysis we can then either parse the data to include or reject it for specific tasks or update the interpretation with the latest ideas. Again, this would be attributed as an update or edit in the database and audited accordingly (in my databases I have a “Compiler” field that lists the initials of the editor and month and year when they made any changes – in corporate databases you may need to have more detail than this).

We need to keep track of all these things in a database if the database is to have longevity and application.

This is not easy.
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The consequence is that within a database we end up with most of the fields being about auditing our data, rather than values or interpretation (Figure 3). 

In spatial databases we also need to understand scale and resolution.

We all ‘know’ what we mean by “map scale”. It is something that is always explicitly stated on a printed, paper map and provides an indication of the level of accuracy and precision we can expect (not always true but our working assumption).

But digital maps are a problem.

Why?

To answer that, ask yourself a simple question “what is the map scale of a digital map?”

To understand this question, open up a map image on your laptop or phone and then zoom in. Is the scale the same before and after you zoom? – measure the distance on the screen!
The answer is of course “No”. The map image may have a scale written on it, but on the screen, you can zoom in and out as far as you want (Figure 4).

This immediately creates a problem of precision and accuracy (see below). How far can we zoom into a digital map before we go beyond the precision and accuracy that the cartographer intended?
In building digital spatial databases we can address this in one of several ways

1. Specify the mapping/compilation ‘scale’ – this is the stated map scale at which the feature was captured on the screen or digitized.
2. Record the size of each feature (this is automatically calculated in most GIS databases)
3. Add an attribute for resolution or size-related – in the Structural Elements Database, we have included a semi-quantitive attribute (Class) that records the impact of the feature on the crust or stratigraphy

As with all data issues, the importance is being aware there is a potential problem here.
​
Two further terms you may find of use when thinking of spatial data are “grain” and “extent”. These are both adopted from landscape ecology. Grain refers to the minimum resolution of observation, for example, its spatial or temporal resolution (Markwick and Lupia, 2002). Extent is the total amount of space or time observed, usually defined as the maximum size of the study area (O'Neill and King, 1998). So, a large scale map may be fine-grained but of limited extent. The key is specifying this for each study. 

Differentiating between precision and accuracy is something of a cliché (see Figure 5). But no less important. A geological observation has a definite location, although it is not always possible to know this with precision, either because the details are/were not reported, or the location was not well constrained originally. Today, with GPS (Global Positioning Systems), problems with location have been mitigated, but not eliminated.

For point data, this can be constrained in a database by an attribute that provides an indication of spatial precision. In my databases, this is a field called “Geographic Precision” (Table 1). The precision of lines and polygons can be attributed in a similar way, although in our databases we have used a qualitative mapping confidence attribute which implicitly includes feature precision and accuracy (see below).

Temporal precision and accuracy are more difficult to constrain in geological datasets. Ages can be made incorrectly, be based on poorly constrained fossil data, or radiometric data with large error bars. In some cases, there may be no direct age information at all, and the temporal position is based on geological inference. Ziegler et al (1985) qualified age assignments based on their provenance, which we have also adopted.

Whilst analytical error is numeric, and sometimes we can assign quantitative values to position or time (± kilometers, meters, millions of years) this is not always possible. So another way to approach the challenge of recording confidence or uncertainty is to have the compiler assign a qualitative or semi-quantitative assessment.
​
In our databases, we again follow some of the ideas outlined in Ziegler et al., (1985), Markwick and Lupia (2001), Markwick (1996). These schemes are distinct from quoted analytical errors and are designed to give the user an easy-to-use ‘indication’ of uncertainty (Table 2). 

The advantage of this approach is that it is simple, which encourages adoption. The disadvantage is that even with explanations of what each code represents (Table 2), there will be some user variation. Nonetheless, it provides an immediate indication of what the compiler believes, which can then be further explained in associated comments fields.
​
In map view, colors can be applied to give the users an immediate visualization of mapping or dating or other confidence depending on what the user needs to know. An example of the mapping confidence applied to structural elements is shown in figure 6. Confidence is further expressed visually using shading, dashed symbology, and line weighting (this is discussed in our database documentation and will be the focus of an article I am writing on drawing maps).

By including fields for record confidence means that the database can be sorted (parsed) for good and bad ‘quality’ data.

Why is this important?

Why not do this on data entry?

You could, for example (and I know researchers who do this) make an a priori decision and remove all data that you believe is poor and not include this in the database.

But what if this ‘poor’ datum is the only datum for that area or of that type of data that you have? For example, in a spatial database, we may have a poorly constrained data point for a basin (we know its location to within 100 km, but no better), but no other data.

That data point is then important or could be, but is spatially poorly constrained – in this case, a low spatial precision.

We need to include this record in our database, because it is all we have. But we need to ensure that the record is audited to reflect the uncertainty in its location.

A priori decisions on which data to include in our database based on an initial assessment of data confidence are therefore to be avoided:

1. This may be all we have
2. This may point us to where we need to actively find more data
3. You can improve/update/replace that datum as better information becomes available – as long as you have attributed correctly

​

Given how much information we need to record to qualify our data, it will come as no surprise that data entry compliance is a major difficulty.

Database population is very tedious. This can result in errors, or short-cuts being taken, or worse.

As an example of what can happen, I had one senior geologist, who will remain nameless, point-blank refuse to attribute his interpretations, stating that GIS and attribution “were beneath him”. After pressure, he acquiesced. But during my QC stage, I found that in a fit of pique he had copied and pasted the same attribution for all records – assigning “Landsat imagery” as the source for submarine features was a bit of a giveaway! All of his work had to be redone, by me as it happened…

This case highlights a serious challenge, to get staff to realize the importance of the audit trail and to fill in these fields.

From my experience let me suggest four ways you can do this (other than threats):

1. Make data entry as clear and as simple as possible. This goes back to something that my friend Richard Lupia and I wrote back in Chicago, that a “database needs to be simple enough to be used, but comprehensive enough to be useful”.
2. Have the data entry teamwork with and update an existing dataset. When faced with a previous entry that does not have enough information to make a decision the new compiler will, hopefully, realize how important including that sort of information is. A common problem is that the data entry team does not use the data. They, therefore, do not have a vested interest in it. Ideally, you need everyone involved in all steps.
3. A rigorous QC workflow – this was something we had at BP when I was an intern spending seven weeks entering data into a wells database. In the late 1980s, this was entered by line code… After completion, the well log was printed and checked by hand by a more senior biostratigrapher. Given this was a bed-by-bed database you can imagine the time and work needed to check every entry. But it was critical
4. Automated QC – design the database so the fields have to be filled in. Dropdown menus, limited options.
5. Automated data entry. For some types of data, this makes sense - capturing data tables -, but care must still be taken. Other automated techniques, such as lineament analysis in structural element mapping are useful to help systematically identify patterns but also can lead to a mess. Such methods still need human interrogation.

 
The solution here is to recognize that technology is there to help you reach answers by removing the most tedious repetitive tasks, and analyzing and managing large datasets. But we must never forget that we still need to know our data. It is a truism that the more remote we get from our data the least likely we are to understand any answers our AI system gives us.
​
We also need to remember that databases are ‘living’ in the sense that you cannot, should not simply populate a database and walk away, but recognize that you need to update and add to your database as more information becomes available.

There is no question that AI and machine learning have much to offer us in data science. But where I worry a little, or perhaps more than a little, about AI is how it is being perceived in many companies as a black-box solution to the problem of big data.

We as users need to have enough knowledge to understand the answers such systems give us, but more importantly, as I hope I have demonstrated here in this brief introduction, we need to ensure that we know where our data has come from and that we trust it. This is not just in the sense of computer verification, but in constraining the nature of the original data itself, how it is recorded, how confident we can be with this recording.
​
This process of qualifying and auditing data is admittedly laborious as my examples of solutions show, but I hope you will have seen how powerful even the simplest schemes can be when used systematically.

​A pdf version of this blog is available here for download.

As some of the more observant readers will have noticed the sediment in the picture at the beginning of this article is not clay, but sand.

​As I have emphasized throughout, you need to know your data – be careful what you build from

Callegaro, M. & Yang, Y. 2018. 23. The role of surveys in the era of "Big Data". In The Palgrave Handbook of Survey Research eds D. L. Vannette and J. A. Krosnick). pp. 175-91.

Damsté, J. S. S., Kenig, F., Koopmans, M. P., Köster, J., Schouten, S., Hayes, J. M. & Leeuw, J. W. d. 1995. Evidence for gammacerane as an indicator of water column stratification. Geochemica et Cosmochimica Acta 59, 1895-900.

Markwick, P. J. 1996. Late Cretaceous to Pleistocene climates: nature of the transition from a 'hot-house' to an 'ice-house' world. In Geophysical Sciences p. 1197. Chicago: The University of Chicago.

Markwick, P. J. & Lupia, R. 2002. Palaeontological databases for palaeobiogeography, palaeoecology and biodiversity: a question of scale. In Palaeobiogeography and biodiversity change: a comparison of the Ordovician and Mesozoic-Cenozoic radiations eds J. A. Crame and A. W. Owen). pp. 169-74. London: Geological Society, London.

O'Neill, R. V. & King, A. W. 1998. Homage to St. Michael or why are there so many books on scale? In Ecological Scale, Theory and Applications eds D. L. Peterson and V. T. Parker). pp. 3-15. New York: Columbia University Press.

Peters, K. E., Walters, C. C. & Moldowan, J. M. 2007. The biomarker guide. Volume 2. Biomarkers and isotopes in petroleum systems and Earth history, 2nd ed.: Cambridge University Press, 704 pp.

Philp, R. P. & Lewis, C. A. 1987. Organic geochemistry of biomarkers. Annual Review of Earth and Planetary Sciences 15, 363-95.

Samuel, A. 1959. Some Studies in Machine Learning Using the Game of Checkers. IBM Journal of Research and Development 3, 211-29.​

Ziegler, A. M., Rowley, D. B., Lottes, A. L., Sahagian, D. L., Hulver, M. L. & Gierlowski, T. C. 1985. Paleogeographic interpretation: with an example from the Mid-Cretaceous. Annual Review of Earth and Planetary Sciences 13, 385-425.

Alexander's restaurant (http://jalexanders.com) at the corner of Westheimer and Wilcrest had long been my refuge. It had been there for as long as I had been visiting Houston. First as Houstons then as Alexanders. A place to relax and think, to meet with friends, enjoy a steak after a long flight or a days’ meetings.
 
My usual dilemma was whether to go for their ‘famous’ baby back ribs or the filet mignon with a béarnaise sauce. Then there was their “vegetable of the day” of which the sautéed spinach, creamed spinach, grilled zucchini, and beefsteak tomatoes are, or rather were, worthy of note.
The baked potato fully loaded was usually a step too far as I saved myself for their wonderful carrot cake. So moist. So bad...
 
And now it was gone…
 
Whilst for many of you the closure of Alexanders is completely inconsequential, especially now, and indeed most of you have probably never heard of Alexanders, for me, it was yet more evidence of changing times and the loss of reassuring certainties. Little did I know…

The oil and gas industry has always been cyclic and many of us have seen many - far too many - downturns and recoveries. Indeed, many old-timers seem to keep track of their careers by the number of downturns they have seen and survived.
 
Each recovery in the past has seen an increase in budgets and a major hiring drive, as business returned to 'normal'.
 
But the last downturn has been different, starting in 2014, and now exacerbated by the consequences of COVID-19.
​
Yes, we as an industry are faced by many challenges, not least the transition from fossil fuels to a more diversified energy portfolio, the vagaries of unconventionals or the political game playing between the worlds leading oil producing countries. Each deserves a blog in its own right.

But the change that concerns me the most, and which I think will have the biggest ramifications not only for our industry but for Earth education in general, is the loss of experience.

As I walked around last year’s AAPG convention in San Antonio I was struck by the greater number of young geologists and the broader diversity of attendees than in previous years.

This was great to see. Change is happening and it is no bad thing.
 
But with all the new faces there was also the demonstrable absence of old faces and with that experience and expertise.
 
it is true that each past downturn has resulted in a gap or pause in the staff demographics as potential graduates looked at what was happening and opted for different careers. The resulting demographic imbalance has been long recognized, and many, if not most companies were actively addressing this through mentoring, knowledge transfer, and digital knowledge and database systems.
 
But the depth and extent of this last downturn have left this process of knowledge transfer incomplete.
​
More significantly, it has seen a generation of experience opt for early retirement and a younger generation who are increasingly deciding against the Earth sciences. This has been compounded by a general reticence to hire significantly this time given uncertainty over the future.
 
The question is, have we lost so much of our experience in this last downturn that this will affect our recovery as an industry and especially our ability to brainstorm and solve the challenges that now face us?

Our industry can boast some of the brightest scientists and engineers of the 20th and 21st centuries.
We have been at the forefront of increasing the understanding of our planet from tectonics, to depositional processes to paleontology and beyond.
Our industry has developed and build technologies and tools that can send sound waves into the Earth to resolve the structure of the subsurface even down to the Moho (the base of the crust) and can now drill through kilometers of rock from rigs sited in two kilometers of water and still know where the drill head is within meters. That is quite incredible. Well, I am still impressed
 
This is something that we should be extremely proud of. Achievements that we should shout about far more than we do.
 
The new generation is equally gifted, if not more so. I have been lucky to hire and work with many excellent young geologists. But they would be even better with mentoring from and access to experienced staff. But those experienced staff have either left or are about to leave the Industry. (As I was about to post this article, I received an e-mail from a friend in Houston who had just announced that she was leaving the Industry. Carmen is one of the most impressive scientists I have worked with and a great role model for the next generation and especially the growing number of young women joining the industry. Her departure is a devastating loss and one the Industry can ill-afford).
 
Experience is key!

This is all the more important as we apply our industry’s skill-base to energy transition and building new business models.
 
Experience is about having seen numerous real-world examples and being able to draw on these when making decisions, warts, and all.  Knowing what worked, what failed, and why.
 
As my Ph.D. advisor repeatedly told me "the best geologists are those who have seen the most rocks". (I am convinced that this is something said by every Ph.D. advisor to every geology Ph.D. student, but that makes it no less true).
 
And that places us in something of a cleft stick.
 
On the one hand, the Industry is addressing past diversity issues and hiring a new generation of enthusiastic, talented, Earth scientists, albeit in limited numbers. Whilst simultaneously cutting costs. Great…
 
But, on the other hand, we have lost the experience and expertise we need to both mentor the next generation and also to make informed decisions as we start to explore once more.
 
So, what to do?
 
Let me respectfully offer a few suggestions:

Today companies have libraries filled with 3rd party reports, internal studies, presentations, and databases. That is an incredibly powerful resource, but only if used.

The challenge is to understand what you have and how to integrate this within your current workflows. What data and knowledge are good? What is bad?  What can you accept and what should you ignore? It is certainly advantageous to know where the skeletons are before you repeat past mistakes! Mistakes cost time and monies.
 
Why spend more monies if you already have the answers, or resources to get to the answers, in-house? 

An easy win is to get your libraries curated and databased. In some companies, this has already been done. It is something I spent 2019 doing with my libraries​ (see my blog on scanning)

Another solution is to bring in the original product builders and get them to explain what they did and where useful, updating their products to fit new corporate workflows. This is certainly where much of my time would have been focussed this year (until some errant RNA intervened), having spent the last 25 years designing, building, and selling products and solutions to exploration companies.

One problem with seeking out the builders is that whilst their companies may still exist (possibly) the authors themselves may have moved on.
​
The same is true when looking for your own staff who made the original purchases with a specific plan in mind and/or who used the products. You may need to visit the golf courses of Houston or drive out to the Hill Country (though obviously not Alexanders) – ‘social distancing’ notwithstanding.

University research groups have always been a great source of cutting-edge ideas, knowledge, understanding, and data. Not to mention future staff.
 
With down-sizing and the disappearance of company-based research groups, universities are becoming all the more important.
 
This is not just about bringing in a professor to give a one-off seminar, but from my experience is best achieved through more active participation through workshops, having academics work directly with teams, and through MSc and Ph.D. projects and internships. 

As an example, last year I participated in a week-long workshop for a company that convened leading academics from different research groups and with varying opinions. In a few days, staff were exposed to all the views and background from the leaders in the field, something that would have taken them months to get a handle on by only reading their papers, and which even then, would not have provided the insights into the mindsets of the protagonists.
 
(There is also a need to maintain a presence in Academia at a time when our industry is increasingly perceived negatively).

Get out the pencil crayons.
​
Get your young staff to look at paper copies of seismic and use colored pencils to identify horizons. The key is to encourage your teams to understand the data, know their data, and to ask questions. They should not be afraid to disagree with their elders, but wise enough to know that experience can be an advantage. We are not infallible, but we have seen more rocks and solved more problems.

​With fewer staff and the disappearance of the armies of specialists we used to have, it is key that the next generation knows how the Earth system fits together.

This does not mean going all "fruit salad" (my thanks again to Catherine for that wonderful imagery), in which our staff have a little bit of knowledge of everything but no real depth.
​
This is about ensuring that our teams know the vocabulary and key headlines of diverse scientific fields and most importantly that they know enough to be able to ask the right questions and know whom to ask or where to search for the answers.

Over the last three years, advances in machine learning and AI have been impressive.

Pattern recognition has indeed been around for many decades: auto-trace in seismic interpretation, or computerized fossil recognition in biostratigraphy. The limitation in the past was largely computer processing power, which is no longer such an issue. 

With data storage now relatively cheap, and especially the development of cloud storage, accessing data and knowledge from anywhere in the world should be child’s play.
​
The problem is that whilst a child can operate an iPad with ease from kindergarten on, if not before, and they are incredibly computer savvy, they do not necessarily know the questions to ask. That comes with experience and does not seem to be always taught. As evidence ask them to do a Google search and see what they find; I am always amazed at what people do not find.

Technology is wonderful, and I am a self-confessed addict having designed, built, managed and analysed computer-based databases for over 30 years. But don't forget the basics - ask questions, know your data, question everything.

Operationally what should we do?

Well that is your call, but let me suggest the following:

1. databasing and data management – curating your data and knowledge so it can be assessed, accessed and analyzed;
2. work with data scientists, who can help design systems that make that data more accessible and program the systems to help us find patterns and get the most from it;
3. have the data scientists work in the same teams as the geoscientists, who know the questions to ask and the significance of the results. 

The future is about preparing our new generations of Earth scientists with all that we have learned over the last century or more, what worked, what failed, and why. To know the questions to ask and where and how to find the answers.

The next generation of Earth scientists needs to be well-grounded in the fundamentals of geology and the scientific method.

At the same time, they need to be conversant with a broad range of scientific fields, or at least enough to know the vocabulary of diverse fields and how each discipline might impact the problem they are trying to solve.

This also gives them transferrable skills that will aid the energy industry as we transition to alternative sources of energy, but also enable them to look at applying their expertise and experience to a range of other challenges, from the management of water resources to carbon capture, and storage (CCS), to geothermal energy, mineral exploration and waste management.
 
They need to be familiar with the tools available, but not to assume they these will solve all the problems they find.

At the end of the day, we need to harness all that we have learned in our industry to accelerate the next generation in understanding even more than we do for the betterment of mankind.

Understanding the Earth is what we do!

A search on the internet revealed that Alexanders Westchase closed at the end of January 2017 on the very same day that I had left my role as Technical Director of an Aim-listed consultancy after 12 years of successfully building the business. Coincidence I am sure…Rule #39 notwithstanding..
 
Today, what was once Alexanders in Westchase, Houston, is the site of a 24-hour emergency center. Useful and admirable, especially right now. Though I won't be going there for steak
 
"Alexanders is closed". All change. 

A pdf version of this blog is available here for download

​2. Make sure you have the right team

A year later, and I found myself self-employed. As an executive director for 10 years, my focus had been on management, strategy, and marketing. But, now here was an opportunity to regain my academic ‘mojo’, to catch up on research, teaching and several decades of scientific papers. An almost impossible task. Thank goodness for Kimbo espresso coffee, good wine and a range of great cookbooks… 

Now, after 24 months I have a major paper published, with several more on the way. New datasets in progress, a completely new data management system and suite of workflows, and an array of new ideas to promote. And most importantly, I have a reinvigorated curiosity about the Earth - my scientific ‘mojo’ is back.

In so doing I also found an answer to my question.

Are we limited to achieving only one big thing?

No. Of course not. We can always do more. It is about time and priorities. And therein lies the issue.

Once we get into our careers, where ever that takes us, time goes quickly. No sooner have we started then we are looking back. For me, it was when I was around 35. Next thing I knew I was close on 55.

There is also the problem that at the very point that we can contribute most to science given our experience, that experience takes us into management where we can no longer do the science. Something is wrong with that surely!
 
So, are there any lessons to learn that might help you if you are in the same position?

Let me suggest a few thoughts: ​

Paleogeographic maps come in a variety of forms. But it is as reconstructions of past landscapes that they are the most useful. Why? Because it is on these landscapes that the geological record is built. A particle sees topography, rivers, and oceans. It experiences rain and floods and the heat from the sun. It does not see mantle convection nor crustal hyper-extension nor differentiate between a compressional or extensional tectonic setting, at least not directly. How sediment is formed in the hinterland through weathering and erosion, transported and ultimately deposited is a function of what happens at the surface and therefore what that landscape is.​

​A Google search for the term "paleogeography" reveals a wide range of maps and images. From simple black and white sketches showing past shorelines to maps of depositional systems or the distribution of tectonic plates, to full-color renditions of paleo-elevation and -bathymetry. Many, if not most, are informative, some are aesthetically quite beautiful.

For most geologists, such maps need little introduction. They have a long history of usage in the literature, and today have become something approaching de rigueur for conference presentations and corporate montages.
 
But paleogeography is more than just images in presentations. It is or can be, a powerful tool for managing, analyzing and visualizing geological information, for investigating the juxtaposition and interaction of Earth processes, as well as acting as the boundary conditions for more advanced Earth system modeling with which to better understand how our planet works.

Over the next few months, I will present a series of blogs that will explore paleogeography.

It will be a journey that will take us through the history of paleogeography, a look at how maps are generated, a guide to some of the pitfalls and caveats of mapping, a review of some of the mapping tools available, as well as examples of how paleogeographic maps have been used to solve real-world problems, especially in resource exploration where I have the most experience.

It is a journey that I hope you enjoy and find useful.

In this first blog, I want to set the scene by addressing two simple questions. What is paleogeography? And why should you care?

The Nature of the Problem: there is simply so much to take in.

If we look at any landscape and the processes responsible for forming it and which are acting on it, such as in the central Pyrenees shown above, we are faced with something of a dilemma: There is simply so much to take in.

For example, if we are teaching field geology in such an area do we focus on the structural evolution, or the stratigraphy, or the depositional systems or the climate, or vegetation or any one of the many components that together comprise the Geological record and the Earth system in this view?

Or do we try and cover all the bases?

Ideally, we want to try and cover everything. But we have limited time. We also do not want to overwhelm all concerned with diverse technical vocabulary and concepts. The risk of losing our audience.

Consequently, we usually focus on a specific field of study.

The same is true in exploration. Whether we are assisting management to make strategic decisions about where to explore or are a member of an asset team identifying and evaluating blocks and then prospects. We need to understand all the components of the Earth system if we are to make informed decisions.
​
30 years ago, companies would have had an army of in-house specialists on whom they could call for help to do this, and even more academic experts on retainers. But, those days have long since gone.

Unfortunately, one thing that has not gone is the budget constraints of the commercial world.

Exploration is, by its very nature, a net cost to an energy exploration business.

So, in addition to the scientific challenges, in exploration, we are also faced with trying to extract the maximum value from limited budgets.

So, what do we do?​

Finding solutions: Paleogeography as a key tool in the geologist’s toolbox
​
We need a tool with which we can bring together (gather), manage, visualize and interrogate diverse geological information, information which is often sparse (especially in frontier exploration areas), sometimes questionable, and often equivocal.

If we look to history for guidance, we find 19th-century geologists faced with the same problem. A growing volume of diverse geological information and how to deal with it.

Over the preceding 100 years, scientists had tried to encapsulate the contemporary knowledge of the Earth system into a single book or series of books. Humboldt's Cosmos or Lyell's Principles are examples. But this had become next to impossible by the middle of the 19th century due to the sheer volume of information, resulting in an exacerbation of the scientific specialism that we have today. Humboldt’s opus itself was unfinished at his death and completed based on his notes.
​
One solution to this problem was to use maps to distil visually this wealth of information. Ami Boué’s maps of the World, more commonly known through Alexander Keith Johnston's “Physical Atlas of Natural Phenomena” (Johnston, 1856) in the middle of the century., or Élisée Reclus’ excellent “The Earth” (Reclus, 1876)

Paleogeography defined

It is no coincidence that Thomas Sterry Hunt, the author attributed with first coining the term “paleogeography”, was also one of the first petroleum geologists, looking for ways to manage and analyze geological data for exploration. (We will revisit this in a later blog).

Paleogeographic maps can summarise a wealth of geological information in a simple, visual way by distilling the record into representations of depositional environments and structures. This then allows additional information to be added and juxtapositions and relationships investigated.
​
Such maps can also show lithological distribution and character, although strictly speaking facies maps are distinct from paleogeography’s in that they represent the product of processes, i.e. the rock record (as do GDEs for that matter), whilst a paleogeography represents the environment and landscape in which and on which those processes act and upon which the geological record is built.

The late Ypresian paleogeography for the central Pyrenees showing one transport pathway that takes in the three outcrops shown.
​From Markwick  (2019)

In practice, this definition of paleogeography has become blurred. Facies maps, GDEs (Gross Depositional Environments), and plate reconstructions are all frequently referred to as “paleogeography”

​The original definition of paleogeography proposed by Hunt was as a field within geology to describe the “geographical history” of the geological record, which to him included the depositional environments, such as deserts and seas (Hunt, 1873).
This view of paleogeography as being the representation of the depositional environments that comprise a landscape is useful for two important reasons.

First, because it allows us to distinguish between the landscape, the processes acting on the landscape, the processes that created the landscape, and the rock record that is the product of all of the above. This makes the Earth system more manageable. It also means that when building a map we can audit each step (something we will look at another time).

But second, it allows us to deconstruct what the rock record directly responds to. What is important to consider. Where we need to focus our time (and monies). If we think of a sedimentary particle formed in the hinterland through weathering and erosion, transported and ultimately deposited, what does it really ‘see’ (i.e. respond to – at the risk of personifying clastic particles too much). A particle sees topography, rivers, and oceans. It experiences rain and floods and the heat from the sun. It does not see mantle convection nor crustal hyper-extension nor differentiate between a compressional or extensional tectonic setting, at least not directly.

It responds to the contemporary landscape and the processes acting on it.

Paleogeography defined: the problem of time
​
We now need to add another component to our definition of what paleogeography is. And that is time.
This is something that was identified by Charles Schuchert, a professor at Yale and colleague of Joseph Barrell, one of the founders of modern stratigraphy.

In summary
​
What is paleogeography?

Paleogeography is the representation of the past surface of the Earth, at a ‘moment’ in time.

Why is it important and why should you care?

Because it allows us to bring together diverse information that will help us better understand the Earth system, whether we are teaching in Spain or faced with deciding on where to explore. Paleogeography gives us the spatial context for gathering, managing, visualizing and analyzing a wide array of geological information in a way that is easy to digest.

At the end of the day, paleogeography is far more than just an image in a presentation.

2018 Edition Contents
 
Welcome to Knowing Earth

Editors Letter
Part of geology’s appeal is its breadth and diversity, bridging the divide between the humanities and the ‘pure’ sciences, borrowing elements from all. Whether we call ourselves ‘geologists’, ‘Earth scientists’ or ‘geoscientists’, the key to understanding the Earth is considering how all the components of the Earth system fit together, interact and evolve through time. But this breadth and diversity come at a cost and nowhere more so than when applied to oil and gas exploration.
 
How the Paleogeographic Atlas Project Redefined Paleogeographic Mapping and Big Data for Exploration
Fred Ziegler’s Paleogeographic Atlas Project was something of an oasis in a building that might otherwise be described diplomatically as architecturally ‘interesting’. If you have ever been to the Hinds building at The University of Chicago you will know what I mean. The office comprised a relatively large work area with three smaller annexes. Large wooden tables occupied the central space surrounded on all sides by shelves filled with books and papers arranged in alphabetical order, each paper in it is own manila folder, each carefully recorded in a reference database, a stamp on its cover to indicate the basics of what it contained. From the resulting databases and atlases, Fred and his team reconstructed past landscapes as paleogeographic maps, developing methods that still define much of how we do paleogeography today. But the Atlas Project also showed how to build, manage and analyze large geological databases. With ‘Big Data’ now prevalent throughout our industry, it is timely to look back to Chicago for some guidance
 
Revealing the Earth’s Architecture  
When Thomas Sterry Hunt first coined the phrase “paleogeography” to describe the reconstruction of the Earth’s geography through time (Hunt, 1873), his workflow began with an understanding of what he referred to as the “architecture” of the Earth. By architecture, he was describing the Earth’s structural framework, crustal geometry and composition, and geodynamics, which today we define broadly within the concept of “Crustal Architecture”.
 
From Source to Sink: the Importance of Drainage Reconstruction
Source-to-sink has become a key concept in exploration, especially for understanding and predicting reservoir facies character and distribution. Source-to-sink follows the path of a particle from its formation through weathering in the basin hinterland, to burial and preservation in a sink area via erosion and transport (Martinsen et al., 2010; Sømme et al., 2009). This is a complex journey that requires an understanding of a wide range of subjects from tectonics to climate, weathering and erosion, transport mechanisms and depositional systems.
 
Modelling the Earth System for Exploration: why some Models are Useful
“All models are wrong, but some are useful”
George Box (Box and Draper, 1987)
 
George Box’s quote has become something of a cliché and one I have frequently heard when promoting the use of climate and lithofacies models in exploration over the past 20 years. Though the usual riposte I receive is with an emphasis on “all models are wrong”. The scepticism levelled especially at climate modelling has many ‘justifications’: “models are not data”, “there are too many uncertainties”, “yesterday’s weather forecast was wrong so how can I believe a climate model?”, “climate change is not real, so the models must be wrong”, “models are models”. Followed by the frequent question “do you have any seismic?”.
 
 Bringing it all Together: the View from the Field
 The 11th century Castillo de Samitier sits precariously upon a Paleocene limestone ridge some 450 metres high above the Río Cinca that winds its way south through the gorge below. All that remains of the ‘castle’ is a small chapel, the Ermita de San Emeterio y San Celedonio, and a single defensive tower, a second having long since fallen into the narrow gorge below.  From the castle, you can see in one view how tectonics, landscape, climate, deposition interacted some 50 million years ago, and how they interact today. The view is breath-taking, but highlights a problem, there is simply so much to take in. 
 
Creating a Legend
Maps are a means of visualizing spatial information. As such, they need a map legend that conveys that information through colour or ornamentation as simply and clearly as possible. In geology, there is a long tradition of colouring and coloured maps, with ‘relatively’ standardized symbologies for chronostratigraphy (geological time), structural elements and lithologies.
 
Further Information
Knowing Earth is about building partnerships and ensuring that all members have a common suite of baseline databases with which to build understanding. For further information, whether commercial or academic, please contact myself or my colleagues.

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