MARYLAND GEOLOGICAL SURVEY 85 



this latter may have occurred in the period regarded as llecent in other 

 regions. The materials which enter into the formations carry a large 

 proportion of ice-borne boulders which could not have been brought in 

 during Pliocene time and are too large to be transported by the moderate 

 development of river-ice now carried out by our streams. These boulders 

 indicate thicker ice and a much colder period than at present. The fossil 

 remains which have been discovered throughout the surficial formations 

 all point to the Pleistocene age of these deposits, but until these various 

 formations have been traced carefully through New Jersey and their 

 relation to the terminal moraine and other glacial deposits determined, 

 it will not be possible to fix the age of the Sunderland, Wicomico, and 

 Talbot more definitely than to say that they are Pleistocene. 



As long ago as 1888, McGee, who was the first to grasp the problem 

 of these surficial deposits, designated a certain portion of them as 

 Columbia and separated them into fluvial and inter-fluvial phases. 

 Later Darton extended the work of McGee and divided these sand deposits 

 'into Earlier and Later Columbia. The author has carried the work of 

 Darton still further and has separated the Columbia formation of 

 McGee into the Sunderland, Wicomico, and Talbot formations. It, 

 therefore, seems appropriate to preserve the name which McGee first 

 proposed for these deposits and to unite them under the broader term 

 Columbia Group. The distribution of the Columbia formations extends 

 from Long Island southward to Mexico and up the Mississippi embayment 

 to the mouth of the Ohio river. This has been represented, together 

 with the distribution of the Lafayette, on Plate II. These formations 

 will now be discussed in the order mentioned above. 



The Sunderland Formation. 



The name Sunderland suggested by a little hamlet in Calvert county, 

 where the formation is well developed, was first proposed by the author 

 in May, 1901. It is equivalent to Darton's Earlier Columbia as described 

 and mapped by him in the Washington folio, U. S. Geological Survey, 

 1901. To the north in New Jerse} r , no formation has been described to 



