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PAUL J. MARKWICK
Geologist
(palaeontology, palaeoclimatology, palaeoecology, palaeogeography, global geology)
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My research interests are broad, as you can gather from the headings at the top of each page on my site: from palaeoclimatology and palaeoecology to global tectonics. All of these interests have to be fitted around my day job, which luckily does partly coincide with my research, though in a more applied sense. But how do these diverse fields fit together?
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My main interest is palaeoclimatology, in particular trying to map and understand the transition from the "hot-house" world of the Cretaceous to the "ice-house" world of the modern day. This requires an understanding of the climate record represented by the geological record (climate proxies), especially the palaeontological record. Hence my thesis on fossil crocodilians (Markwick, 1996, see also 1998).
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Climate proxies represent the consequences of climate, whether through direct physical and chemical constraints (e.g. evaporites) or via biological adaptations to a specific environment. All climate proxies occupy a position in 'climate space' and the aim of my research has been to try to define that space quantitatively.
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But geological data is not an impartial witness to the past and is inherently biased. Such heterogeneity needs to be understood and qualified as it does in many fields of research today and in the end this comprised much of the thesis (Markwick, 1993, 1998), including the compilation of taphonomic control groups (i.e. all other vertebrates!). This heterogenity also had to be included in the databases set up to store the climate proxy data that I still continue to compile and analyze, and this in itself proved to be a major problem that needed to be solved (see Markwick & Lupia, 2002). In addressing these issues Richard and I made use of existing terminology borrowed from Landscape Ecology, where the issue of scale is a similar problem: GRAIN - the resolution of the data; EXTENT - the area/scope of the study.
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A full understanding of palaeontological climate proxies also requires an understanding of the ecology of each group, their biogeography and evolution. To address this I have also compiled a large dataset of modern vertebrates and plants. This provides a means of quantitively describing the climate space represented by specific taxonomic groups at any required taxonomic level. The initial results of this study were first presented as a poster at the SEPM meeting on the "Stratigraphic Record of Global Change" at State College in 1993 (Markwick, 1993), with the data relating to crocodilians and also turtles being included in the thesis (Markwick, 1996). The basic large-scale results (concentrating on the link between biodiversity and climate) have been since published in a Special Publication of the Geological Society, London (Markwick, 2002), and I hope to get more of this dataset into the public domain as soon as time allows.
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Mapping climate proxies provides a spatial description of contemporary palaeoclimate, but that description has to be placed in a spatial context. This is provided by palaeogeography. Since palaeogeography is also a critical boundary condition for climate models (GCMs), detailed, well constrained global palaeogeographies are essential. Building on techniques learned at Chicago as a member of Fred Ziegler's Paleogeographic Atlas Project, I have developed a series of Cretaceous and Cenozoic palaeogeographies, which are now being revised to include palaeo-bathymetry and palaeodrainage, and then converted to a digital elevation model (PalaeoDEM). The aim is to ultimately produce a fully evolving landscape model. This is an ongoing project and although a DEM for the Maastrichtian has been finished (Markwick, 2001) progress on the remaining maps is currently being limited by the time limits set by having a full-time Industry job.
In addition I continue to pursue a research interest in the tectonic evolution of southern Greece with Dr. David Rowley (University of Chicago). This work has direct implications for the evolution of Apulia and thereby revisions to the plate reconstructions, upon which the palaeogeographies are drawn.
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With detailed global palaeogeographies as boundary conditions and hypotheses drawn from examination of climate proxy data, the next step is to model the climate in order to try to understand the dynamics responsible for observations. This work is done in collaboration with Professor Paul Valdes. The climate proxies can then be used to quantitatively assess the success of General Circulation Model (GCM) experiments. Conclusions about the veracity/limitations of models has explicit consequences for understanding the correctness of future predictions
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In drawing diverse fields together there are a number of other questions that become important and applications that can be derived. Early in my PhD work one such issue was the question of Eustacy and the history of the cryosphere. With Professor David Rowley we examined the consequences of a literal acceptance of the Exxon 3rd order eustatic sea-level curve and found that it explicitly required large ice-sheets throughout the Mesozoic and early Cenozoic for which there was no unequivocal evidence (Rowley & Markwick, 1992; Markwick & Rowley, 1998). This suggested to us that the eustatic interpretation of the Exxon curves was either exagerrated or in error. Our conclusions have major implications for regional stratigraphic correlations based on sequence stratigraphy, which is used extensively by oil and gas explorationists. A new study on this problem is in preparation.
Another consequence of this research has been the development of palaeodrainage systems as an important part of the geographies and a prescribed boundary condition for the current generation of coupled ocean-atmosphere GCMs (Markwick, 2001; Markwick et al. 2002; Markwick & Valdes, 2003). Not only does this allow freshwater fluxes to the ocean to be calculated, but also general erosional and sediment transport patterns. This is ongoing research.
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All of this work has been greatly faciliated through the utlization of Geographic Informations Systems (GIS), in particular ARC/INFO, ArcView GIS and ArcGIS 8 developed by ESRI. GIS has been central to Generation 1 of my recently completed set of detailed stage-level palaeogeographies for the Aptian to Recent (Markwick, P.J., et al., 1999), and now to the development of palaeoDEMs and analysis of the latest coupled ocean-atmosphere model results.
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So all of these diverse interests do have a logical relationship. The importance is being able to understand enough of each to be able to act as link between the various experts in each field. Only through a holistic view of the Earth System and constant questioning will the Earth System be truely understood. Consequently, I believe that my research has implications not only for the field of Geology as an academic pursuit (interesting as that is), but also in addressing modern issues that affect (or will soon affect) all of us: from climate change and it's consequences, to biodiversity, to oil, gas and mineral exploration, to water management and insurance. The only limitation is time!
And what do I do in my spare time? You jest! Well, I do enjoy cooking, travel, hiking, the odd game of field hockey (and no "odd" doesn't refer to the way I play) and landscape photography. Although at the moment sitting in front of good film like "Moulin Rouge" seems to be about my limit!
I hope you find this web site of interest and please do contact me with constructive criticisms, offers of wine and chocolate... !
All the best
Paul
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