No. 4.— Postglacial and Interglacial (?) Changes of Level at Cape 
Ann, Massachusetts. By R.S. Tarr. With a Note on the 
Elevated Beaches. By J. B. Woopworta. 
Nature of the Work. — Investigation upon the recent geology of Cape 
Ann was begun by me in 1887 in connection with work for the United 
States Geological Survey under the direction of Professor Shaler. The 
results obtained during that period have been published in the Ninth 
Annual Report of the United States Geological Survey (pp. 529-611). 
Since that time frequent visits to the region have furnished opportunity 
for further study, attention being specially directed to tracing the evi- 
dence of recent elevation along that coast. The discovery of well-defined 
beaches and other evidences of uplift, first made in 1887, received very 
distinct support from these later studies, and it is a statement of these 
additions to the evidence proposed by Professor Shaler that constitutes 
excuse for this paper. ; 
In the prosecution of the work very material aid has been given by 
Mr. John L. Gardner, whose interest in the investigation led him to gen- 
erously undertake the expense of a careful, detailed survey of some of 
the most pronounced beaches ; and the maps which were made for this 
purpose by Prof. A. E. Burton of the Massachusetts Institute of Tech- 
nology are used as illustrations ia this paper (Plates 2, 3, and 4). 
The preparation of these maps is a matter of distinct importance, since 
they place on record the form and elevation of these beaches, which are 
in danger of speedy destruction because of the encroachment of summer 
residences upon their sites. 
Stripped Areas and Stratified Deposits. — The evidences that the sea has 
covered the coastal margin of Cape Ann at least up to an elevation of 40 
to 60 feet above the present level are very distinct and of several kinds. 
In the first place, as clearly stated by Professor Shaler, while the 
center of Cape Ann is heavily strewn with morainal deposits, the coastal 
strip is almost clear of such accumulations and is marked by a distinct 
predominance of bare rock. Above an elevation of from 50 to 60 feet 
the soil is almost entirely morainic till, more sandy than is common*in 
many regions, but nevertheless distinctly unstratified. Below this ele- 
VOL. XLII. — NO. 4 1 
