NORTH AMERICAN PHANEROZOIC PALEOGEOGRAPHY: BOB DOTT INFLUENCES ON RECONSTRUCTING ANCIENT LANDSCAPES (Invited Presentation)

Paleogeographic maps are both syntheses of volumes of geologic data and hypotheses that interpret these data in a comprehensible format. Early versions from the 19^thand early 20^thcenturies were mostly pen-and-ink sketches that attempted to show broad concepts related to the distribution of land, seas, and mountains. As geologic data increased exponentially during the middle and late 20^thcentury, paleogeographic maps improved in accuracy, detail, and sophistication. Bob Dott was involved in this growth of paleogeography as a discipline. Marshall Kay was Bob’s advisor at Columbia University, where Bob earned his doctorate. Kay, along with Erwin Raisz, published a spectacular pen-and-ink drawing of an Early Ordovician landscape. This map and others like it inspired Dott to construct his own series of maps, resulting in his 1961 “Paleogeographic Maps of North America”; “A Study Supplement for Historical Geology” workbook, co-authored with Roger Batten, was used in Historical Geology at the University of Wisconsin. In the late 1960s, Bob published a series of plastic relief paleogeographic maps of North America. This was followed in the early 1970’s by the first edition of Dott and Batten, Evolution of the Earth, which included paleogeographic maps of each geologic period, along with wind patterns and the paleoequator. These maps were accompanied by isopach maps and sedimentary facies maps.

Bob Dott used paleogeographic maps extensively in his teaching. It was not unusual to see a handful of students arrive early at his Historical Geology class to watch him construct the detailed, chalk-drawn paleogeographic maps that would illustrate his lectures. In lab and in discussion session, students would ponder over his paleogeographic maps in the workbook.

Bob’s work inspired others, most notably A.M. Ziegler, at the University of Chicago, and his student, Christopher Scotese, who published a series of papers illustrating paleogeography of the world based on detailed and exhaustively collected data. One of us (Blakey) was also inspired to produce realistic renderings of the Earth’s surface at various times.

Paleogeographic maps have been used to study paleobiogeography, global paleoclimate patterns, and global albedo, as well as providing invaluable context for regional studies.