arowtail1.jpg (4929 bytes)

History of the Atlas

This Paleogeographic Atlas, is just one of a series of atlases, that I have produced since my days as an undergraduate at the University of Illinois (Chicago). The first atlases were published as miniature "flip books" (Scotese, 1975; 1976; and most recently, Scotese, 1997) and computer animations (Scotese and Baker, 1975; Scotese et al., 1981). While a graduate student in Fred Ziegler's lab at the University of Chicago and Rob Van der Voo's paleomagnetic laboratory at the University of Michigan, we published a series of maps which were a unique combination of plate tectonics, paleomagnetism, and paleogeography (Paleozoic maps, Scotese et al., 1979; Mesozoic and Cenozoic maps, Ziegler et al., 1983). Though other paleogeographic atlases have been published (Smith et al., 1994; Ziegler, 1989), as far as I am aware, these early publications of the Paleogeographic Atlas Project were the first maps to illustrate the plate tectonic and paleogeographic evolution of the ocean basins and continents during the Phanerozoic.

Though based on this early work, the paleogeography has been updated as more recent syntheses have become available for the Jurassic & Cretaceous (Scotese, 1995), Africa (Hulver, 1985), Europe (Ziegler, 1989, 1990), China (Wang, 1985; Nie et al, 1990), Australia (Cook, 1990), SE Asia (Hutchison, 1989), Former Soviet Union (Zonenshain et al., 1990), and globally (Ronov et al. , 1984, 1989).

It is important to note that in 1982, Judy Parrish, who was a post-doc at Chicago at the time, added her paleoclimatic interpretations to these early reconstructions (Parrish, 1982; Parrish et al., 1982). Judy's paleoclimatic reconstructions are the basis of the climatic zones shown in this atlas and were the inspiration for the parametric climate model (PCM) developed by Malcolm Ross and myself (Scotese and Summerhayes, 1986; Scotese and Ross (in prep).

In 1984, at the invitation of John Sclater, I joined the research staff at the Institute for Geophysics and started the Paleoceanographic Mapping Project (POMP) - now the PLATES Project. The goal of POMP was to assemble a global, digital compilation of linear magnetic anomaly data and to map the tectonic features of the ocean floor using data from satellite altimetry (Gahagan et al., 1988) in order to construct a comprehensive plate tectonic model describing the development of the ocean basins during the Mesozoic and Cenozoic. This work was carried on in collaboration with Larry Lawver, John Sclater, Dietmar Mueller, Christophe Heubeck, Jean-Yves Royer, David Sandwell, Lisa Gahagan, and Malcolm Ross.

In 1987, Will Sager and I, convened a symposium on Mesozoic and Cenozoic plate tectonic reconstructions at Texas A&M University. A symposium volume (Scotese and Sager, 1988) documented, on an ocean by ocean basis, the plate tectonic constraints used to reassemble the ocean basins and continents during the Mesozoic and Cenozoic. The Mesozoic and Cenozoic development of the ocean basins shown in this atlas are based on these plate tectonic models (Scotese et al., 1988). The work begun at Texas has also born fruit in the form of the global hotspot models of Mueller et al., 1994, and a digital age of the ocean floor database (Mueller et al., 1996).

Though sea-floor spreading data are sufficient to reconstruct the ocean basins, other information must be used to unlock the Mesozoic and Cenozoic history of the complex convergent belts in China, S. E. Asia, the former Soviet Union, and the North American Cordillera. The model presented here for China grew largely from informal discussions with David Rowley, Fred Ziegler, Nie Shangyou (Nie et al., 1990; Yin and Nie, 1996) and Celal Sengor (Sengor and Natalin, 1996). The early paleomagnetic syntheses of Lin Jin Lu, were also very useful and thought provoking. The treatment of the terranes of the former Soviet Union is based on the magnificent synthesis of Lev Zonenshain and his colleagues (Zonenshain et al., 1990). The treatment of the exotic terranes of the North American Cordillera is derived largely from the work of Friedman (1983) and Rowley (1992).

The Mesozoic and Cenozoic history of the ocean basins and continents is relatively well understood when compared with our knowledge of the Paleozoic. In the summer of 1988, a symposium on Paleozoic Palaeogeography and Palaeo- biogeography was co-convened with Stuart McKerrow at Oxford. The goal of that symposium was to produce a new set of Paleozoic reconstructions (Scotese and McKerrow, 1990) and test them with available biogeographic, paleomagnetic and paleoclimatic data. The Paleozoic maps shown in this atlas are based on the results of that symposium (McKerrow and Scotese, 1990; Scotese and Barrett, 1990).

It is interesting to note that the oldest paleogeographic reconstruction in this atlas (Vendian Ice Age, 650 Ma), was the last map to be assembled (Scotese et al., 1993; Scotese, 1997). In the early-1990's, as a result of the pioneering work of Moores (1991), Dalziel (1991), and Hoffman (1991), it became clear that the late Proterozoic was a time of supercontinent assembly (Rodinia - 1100 ma), subsequent breakup (approximately 750 Ma), reassembly (Pannotia, 600 Ma), and breakup (550 Ma) (McKerrow et al., 1992). Preliminary paleomagnetic syntheses (Powell et al., 1993; Meert and Van der Voo, 1994) also suggested that most of the Vendian glacial deposits were deposited at high paleo-latitudes. The Vendian paleogeographic map presented here is based on a model of late Proterozoic plate tectonics developed by myself, Damien Nance (Ohio University) and W.S. McKerrow.

The Next Atlas: A Digital Version

Our understanding of the plate tectonic, paleogeographic, and paleoclimatic development of the Earth is an on-going project. Maps such as these, are at best a milestone, a progress report, describing our current state of knowledge and prejudice. In many respects these maps are already out-of-date. New paleomagnetic data summaries are available (Van der Voo, 1993; Bocharova and Scotese, 1993), hot spot models have been refined and debated (Mueller et al., 1994), satellite altimetry data has revealed the ocean floor in unprecedented detail, plate tectonic models have been updated for Asia (Sengor and Natalin, 1996), China (Yin and Nie, 1996), the Arctic & Circum-Pacific (Monger and Nokleberg, 1996), S.E. Asia (Rangin, 1990; Betrande and Scotese, 1993; Hall and Blundell, 1996), the Former Soviet Union (Zonenshain, et al., 1990; Bocharova, 1993), the regions surrounding Antarctica (Storey et al., 1996), and the early Paleozoic (Dalziel, 1997; MacNiocall et al., 1997; Jurdy et al., 1995; Cocks et al., 1997).

Detailed paleogeographic maps are now available for many parts of the world: Mesozoic and Cenozoic coastlines (Smith et al., 1994), North America (DNAG series; unpublished paleogeographic maps of Cook and Bally, 1975), Tethys (Dercourt et al 1994), Gondwana (Veevers et al., 1996), the Permian (Scotese and Langford, 1995; Ziegler et al. 1996), and the K-T boundary (Upchurch et al., in press ). Paleoclimatic simulations have been run form numerous time periods (Barron et al., 1994; Fawcett et al., 1994; Golonka et al., 1994; Kutzbach and Ziegler, 1994; Otto-Bliesner et al., 1994; Valdes and Sellwood, 1992; ), and a global, Phanerozoic database of lithologic indicators of climate has been assembled to test the results of the climatic simulations (Boucot et al., in prep.).

All of these results, and more, must be incorporated in the next version of the Paleogeographic Atlas. But how?

Though some aspect of the "next atlas" will be published as a series of maps such as these, I envision that the next atlas will be a "digital atlas". GIS technology, especially programs such as ArcView*, now allows users to view and interact with the geographic data in a dynamic and flexible way. Map information in the form of points, lines and polygons can be queried based on attributes and replotted instantaneously in a variety of map formats and scales.

A Paleo-GIS program has been developed jointly by the PALEOMAP Project and Earth in Motion Technologies. The Paleo-GIS runs under ArcView 3.0 and produces plate tectonic reconstructions for any period in Earth history from the Late Precambrian (750 Ma) to the present-day. The Paleo-GIS will be the foundation upon which the next generation digital Paleogeographic Atlas will be built.


References Cited