250 New York State Museum 



The name Canadian was first used as a group name 

 (Dana '74) for a series of formations (Lower Ordovi- 

 cian) which were well-developed in northern New 

 York and Canada, from which country the name was 

 taken. The separation of this group from the Ordovi- 

 cian as a distinct system has recently been proposed 

 (Ulrich '11) ; and the name of the group was retained 

 for the system, which is set off from the Ozarkian be- 

 low by a complete break and is also marked at the top 

 by a complete break throughout North America. 



The close of the Ozarkian and beginning of the 

 Canadian is marked by a general withdrawal of water 

 from present land areas. Nowhere has continuous de- 

 position been found from the Ozarkian into the Cana- 

 dian. The returning waters assumed a different ar- 

 rangement, and the trangressions of the sea at least 

 in two stages during this period were more extensive 

 than the trangressions that occurred later in the Or- 

 dovician (Lowville and Trenton seas). The sea gradu- 

 ally occupied the country in the Acadian area of Can- 

 ada, in eastern and central United States and in the 

 Cordilleran area. There was pronounced submergence 

 in Nevada and Utah. The period therefore was one of 

 emergence with deposition over wide areas at certain 

 stages, and it was also a period essentially of dolomite 

 making. The aggregate thickness of Canadian de- 

 posits is somewhere around 7000 feet mostly lime- 

 stones and dolomites. The greatest thickness in the 

 east is found in the middle and southern Appalachian 

 area; in central United States, in Oklahoma; in the 

 west, in the Rocky Mountains region of Nevada and 

 Utah. In New York the Beekmantown limestone of 

 this age is replaced in the Hudson valley near Albany 



