122 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
of rivers and lakes; perhaps they were of migratory habits like the 
present salmon; (3) the alternations of sediments, which are frequently 
cross-bedded and preserve foot-print and raindrop impressions, in- 
dicate the prevalence of high tides; the presence of land plants in 
the more carbonaceous portions of the deposit, and of fossil wood in 
sandstone in many localities indicate the proximity of land. Russell 
also reports (ibid., p. 33) from the Connecticut valley a coarse con- 
glomerate which sometimes contains rounded boulders two to three 
feet in diameter and occurs along the eastern margin but is seldom 
found on the western border. In the southern areas, on the other hand, 
the Newark rocks have conglomerate exposed on the western border 
but seldom on the eastern border. 
Glacial Deposits. In the attempt to discover the origin of coarse 
and irregularly deposited materials appeal has often been made to 
glacial action, sometimes without due regard to the features that might 
be expected to appear if glaciers were really concerned. It becomes 
important, therefore, to examine the characteristics of the accumula- 
tions of the glacial period and of earlier deposits assigned to glacial 
origin, in order that true criteria for judgment may be obtained. 
Neglecting morainic heaps of great boulders and the erratic blocks 
that are so numerous-in certain localities, the discussion will be con- 
cerned chiefly with those deposits that either are conglomeratic or 
resemble conglomerates in some of their characteristics, and with the 
finer associated sediments. 
One of the most important glacial deposits is till. This material has 
been described by numerous writers. According to J. Geikie (p. 7- 
15) it is a tough, tenacious, stony clay that has evidently been sub- 
jected to great pressure. It often becomes coarser and sandier and in 
certain districts may be described as a coarse agglomerate of subangu- 
lar and angular stones set in a scanty matrix of coarse earthy grit and 
sand. Sometimes the stones are so numerous that hardly any matrix 
is visible. The stones vary in size from mere grit and pebbles up 
to blocks several feet or even yards in diameter; the last are less 
abundant than the smaller materials. Perhaps stones varying from 
two or three inches to six or eight inches predominate. They are 
neither round nor oval, like river gravel or sea shingle, nor sharply 
angular. ‘The sharp edges and corners are smoothed and the stones 
are scattered in pell-mell confusion. They are smoothed, polished, 
and striated and have the more pronounced striations parallel to their 
length. The materials are generally local in character and some- 
times there is a rude stratification. When the layers separate, the 
