40" The American Geoloylst. July, 1895 
dins of six miles from the center of the city the only eleva- 
tions even one hundred feet higher than the plain are the 
range of hills known as the "PinnHcle hills,"' lying at the south 
border of the city. With their conspicuous position, unusual 
topography and complex structure these hills have not escaped 
the notice of glacial geologists, but until 1892 no one ventured 
any detailed description or any explanation of their origin.* 
During the meetings of the Geological Society of America 
and the American Association for the Advancement of Science 
in Rochester, August, 1892, the geologists in attendance vis- 
ited and subsequently discussed them brietly in '\Section E." 
At the Ottawa meeting of the Geological Society in December 
of that year Mr. Warren Upham read a paper describing these 
and other deposits of the region under the title "Eskers near 
Rochester, N. Y.," which was subsequently published in the 
Proceedings of the Rochester Academy of Science. f In that 
paper Mr. Upham describes the hills with considerable detail 
and concludes that thej^ were deposited "in the ice- walled 
channel of a stream of water," ''open to the sk}'." Since that 
time the w'riter has been able to make a long and close study 
of these peculiar hills and lias been forced to a conclusion 
radically different from that of his friend, Mr. Upham. The 
opinion as to their origin, which the writer holds with full 
confidence, is that the hills are a kame series forming part c»f 
a frontal moraine. (See Plate III.) 
Mr. Upham's brief examination of the hills was made under 
the disadvantages that the forests were in full leaf and the 
gravel pits in active working. Only when the thick timber 
and undergrowth which covers the roughest portions are bare 
of foliage does some of the most significant topography ap- 
pear to good advantage ; and the structure of the finer sands 
is developed by the wind only w'hen the walls of the pit are 
*The earliest publislied reference to these hills is in Dr. James Hall's 
report on the Fourth (Teological District of New York. Professor Ches- 
ter Dewey reco.uiii/.ed their iiiacial characler, so the writer is infornietl, 
but no writinii' of his relalin.ir to them has been found. In the Amkui- 
CAN Gkologist, \()1. v. p. 202-207, April, 18i)0, Dr. Charles R. Dryer, in 
an article upon (lie "(ilaeial (ieoloyy of the Irondequoit Rejjion,"" refers 
brieHy to the hills. 
jYol. II, pp. 181-20U, February, 1893. 
