54 McGEE MEMORIAL MEETING 



quake McGee was sent at once to the scene of the disaster, and 

 he obtained a large number of data used later by Button in his 

 report. 



McGee's principal fields of personal investigation in geology were 

 northeastern Iowa and the Atlantic and Gulf Coastal Plain. He also 

 assisted Russell in the Lake Lahontan work and made a survey of 

 part of Macon County, Missouri. His work in northeastern Iowa, 

 which covered an area of 20,000 square miles, was done privately as 

 already stated, before he became a member of the Geological Survey, 

 although some supplemental work and the publication of the report 

 were at governmental expense. In the Coastal Plain his observations 

 were mainly from Maryland southward, and while some of the minor 

 details of the classification and identification of deposits may not 

 be verified at every point, the differentiation of the Potomac, Lafay- 

 ette, and Columbia formations was one of the most important geo- 

 logic contributions we have had. It matters but little whether or 

 not the type locality of the Lafayette proves to be valid and that 

 some marginal red sands are Eocene, for McGee made a master stroke 

 in recognizing the fact that our coastal plain is covered by a wide- 

 spread mantle of littoral deposits representing Pliocene time. It was 

 recognized over an area of 300,000 square miles and was of greatest 

 significance in the history of the continent. McGee's first name for 

 this formation was the Appomattox, and its correlation with Lafay- 

 ette was a later idea. When I began my association with McGee 

 this formation had not been recognized north of the James River, but 

 I found that it extended across Virginia and Maryland, and some 

 outliers remained in New Jersey. The Potomac formation has proven 

 to comprise a group of stratigraphic units varying in range in different 

 regions, but widely separated from the Newark group below and from 

 the marine Cretaceous above. It included the deposit which I sepa- 

 rated later as Magothy formation but aside from this it remains as a 

 distinct group. 



The recognition of the Columbia formation was of great signifi- 

 cance to geography as well as to geology. It was correlated with 

 the earlier glacial deposits and found to cover nearly 150,000 square 

 miles of the coastal plain. Its topography and components have most 



