POST-GLACIAL HISTORY OF BOSTON 



By Hervey W. Shimer. 



Received December 13, 1917. 



CONTENTS. 



Page. 



Introduction 441 



Description of sections 442 



Tabular list of species 448 



Notes on species 450 



Conclusions 456 



Bibliography 463 



Introduction. 



The time from the close of the Glacial Period, from the melting 

 back o^ the glaciers which lately covered this region, to the present, 

 is full of interest. For it is this post-glacial time which tells us of 

 our own immediate past; it tells us of the recovery by organisms of the 

 uninhabited glacier-covered lands. It gives us the history of these 

 organisms and through them of the topography and climate of the 

 region. The records of these organisms, in the Boston area, are mainly 

 preserved in the mud deposited here during this time. This mud 

 was partly laid down in shallow fresh-water swamps but mostly in 

 sea-water, in inlets from the ocean. Naturally the majority of these 

 records consist of the remnants of plants, and especially of shells, 

 though there are also one or two records of early man. 



One of the earliest persons to make a broad study of the post-glacial 

 fossil shells of Boston was Miss D. L. Bryant (1). This subject formed 

 the theme of her graduating thesis in geology in 1891 at the Massa- 

 chusetts Institute of Technology; it was pursued under the efficient 

 help of Professor \V. O. Crosby. Unfortunately it was never published. 

 Later on during the same year, however, Mr. Warren Upham (3) used 

 Miss Bryant's principal facts and conclusions (for which he gave 

 full credit) in the preparation of a paper on the " Recent fossils of the 

 Harbor and Back Bay, Boston." This is an excellent little pamphlet 

 full of information concerning these Post-Pleistocene fossils. In 

 1903 Professor W. O. Crosby (2) discussed the bed rock of this area 

 with reference to the pre-glacial drainage, the deposition and subse- 

 quent erosion of the blue glacial clay and the deposition of the silt. 



In the preparation of the present paper we have drawn freely from 

 these three pamphlets. The notes and the additions here made to 



