THE 
AMERICAN NATURALIST. 
VoL. x1.— OCTOBER, 1877. — No. 10. 
NOTES ON THE SURFACE GEOLOGY OF EASTERN 
MASSACHUSETTS. 
BY W. O. CROSBY. 
a prevalent line of strike in Massachusetts, as is well 
known, is north and south, and in the western half of the 
State there are no exceptions of importance to be noted. East 
of the Nashua Valley, however, a northeast and southwest 
strike prevails, especially in Essex and Middlesex counties; a 
comparatively limited area in the southeastern part of Worces- 
ter County exhibits a strike at right angles to this, or north- 
west and southeast; while among the Primordial and Carbon- 
iferous strata, a nearly east and west strike is most common. 
“ Geology is revealed in topography,” and these fundamental 
structure lines find distinct expression in the leading topo- 
graphic features of the State. In the Connecticut Valley and 
Berkshire County, where the geologic structure is simplest, this 
correspondence between geology and geography is most marked, 
and is observable not only in the grander features, —such as 
the Taconic and Hoosac ranges of mountains, and the Housa- 
tonic and Connecticut rivers, — but may also be readily traced 
In the courses of most of the minor streams and subordinate sur- 
face reliefs, East of the Wachusett range of highlands, we find, 
with greater complexity of geologic structure, two general topo- 
gtaphic trends. The more prominent of these shows a close con- 
formity with the prevalent strike, — northeast and southwest, 
varying toward east and west; while the other coincides with 
> transverse strike and the known direction of glacial move- 
nent. 
Water and ice are the principal agents by which the topog- 
raphy of this region has been fashioned. Now there is little 
toom to doubt that the sculpturing done by water exhibits, on 
Copyright, 1877, by A. S. PACKARD, JR. 
