500 C. SCHUCHERT PALEOGEOGEAPHY OF NORTH AMERICA 



In the column marked "Kegional movements" is indicated the character 

 of land movement for the times specified, which in most cases are times of 

 folding. The border region so affected is also noted. This information 

 is probably not accurate, but is thought to represent at least the major 

 movements. It is not intended to record here the warnings of the areas 

 of the continental seas, as these movements are thought to be too slight in 

 amount to effect the major transgressions and emergences. 



The column "Seas present" gives the names of all the bodies of water 

 existing at each period. The letters are arranged according to the impor- 

 tance of the various seas — that is. according to the amount of area covered 

 by them — the following seas being represented : 



Ap = Appalachian sea. H = Hudson sea. 



At == Atlantic ocean. L — Saint Lawrence sea. 



Ar = Arctic ocean. M — Mississippian sea. 



C = Cordilleran sea. P = Pacific ocean. 



G == Gulf of Mexico. S — Sonoran sea. 



The column marked "Direction of flow of water — in or out"' indicates 

 the ocean transgressing (-J- P. means from Pacific), and the direction of 

 now of the waters during an emergence ( — G. means towards the Gulf ) . 



The column "Kate of change of strand-line''* shows the relative geo- 

 logic rate at which the transgressions and emergences take place. The in- 

 formation in this column should be used cautiously, and especially in 

 regard to emergences, for one's judgment as to the amount of time re- 

 quired to change a given fauna appearing above an hiatus may be de- 

 cidedly at variance with fact when discovered. 



Regional movements. — During the eleven periods of Paleozoic trans- 

 gressions there were but three of land folding, and of these only one 

 may be said to be noteworthy, as far as the area affected is concerned. 

 This is the one of Onondaga time. The eleven emergences record nine 

 periods of movement, of which three were decidedly great, the one at the 

 close of the Georgic period, and the Taconic and Appalachian revolutions. 

 Four others were less strongly marked (Shakopee, Onondaga, Chemung, 

 and Kaskaskia), and the two remaining are of small significance ( Utica 

 and Fern Glen) . Of the nine post-Paleozoic divisions of the table, two 

 record no movement — the Triassic and Oligocene — that of the Eocene is 

 not of special importance, while the remaining six are of much force, espe- 

 cially the Laramide revolution. In other words, of the thirty-two tabu- 

 lated divisions of geologic time, fourteen record no movements, four only 

 slight ones, and fourteen times there were marked movements. 



As far as the Xorth American continent alone is concerned, it appears 

 as if the invasions or transgressions of the oceans had but slight connec- 



