( 386 ) 



Similar bowlders have been found on the mainland of 

 eastern Massachusetts, but so far as I am informed, the loca 

 tion of the outcrop from which they were derived has not 

 been satisfactorily ascertained. This problem is an interest- 

 ing one and its correct interpretation would materially assist 

 in determining the exact direction of glacial movement in 

 that region. 



Those who may be interested in the general subject of the 

 Cambrian rocks of the adjacent mainland will find an excel- 

 lent contribution, with numerous references to other authors, 

 by A. W. Grabau, under the title "Palaeontology of the 

 Cambrian Terranes of the Boston Basin. "* 



3. Provincetown. 

 (a) Geology. 



From the Highlands of Truro, northward and westward 

 around to the extreme end of the cape, lie the sand dunes 

 and beaches of Provincetown, embracing an area approxi- 

 mately six miles long by an average of two miles wide, and 

 including hills which reach elevations of ninety feet and more 

 above tide, every natural feature of which region is a product 

 of wave or wind action in recent geologic time, that is, since 

 the close of the Ice Epoch. * 



A study of these features is exceedingly instructive, not 

 only for the reason that they supply such obvious indications 

 of the manner in which the forces of nature have acted in 

 the past but also because they afford such striking examples 

 of what is taking place at the present time. Many of the 

 phenomena of erosion and transportation are so perfectly 

 apparent and easy of interpretation that any observer can 

 hardly fail to be impressed by them and to me they appealed 

 irresistibly, on account of the intimate relations which were 

 seen to exist between the geological and botanical factors 

 involved. 



* Occasional Papers, Boston Soc. Nat. Hist. 4 : Pt. III., 601-694. //. 31-39- 

 1900. 



