898 THE AMERICAN NATURALIST. (Vou. XXXII. 
of deposition around an interior basin, the Taconic system as a 
changed Silurian system, mountains as rock heaps, faunal cate- 
gories, and cycles. 
This illuminating power was indeed due to a certain plain- 
ness in Hall’s mind that led him to reject arduous and difficult 
theories. And it led him on the straight sunlit path when a 
more abstruse mind would have been, with great effort, work- 
ing away from the truth underneath the ground. The work of 
correlation of the fossil horizons of the United States, done by 
Hall, was largely based upon fossil evidence as well as topo- 
graphic continuity, and this correlation personally established 
by himself, as it was more and more supported by fresh evi- 
dence and new workers, laid bare the simplicity of the geology 
of the east and middle United States. 
Indomitable in desire as he was in spirit, Hall reached the 
Rocky Mountains and established some of the first identifica- 
tions of the Cretaceous in the west, and had begun there to 
show its varying character. 
It belongs to the sensibleness of the man, the quality that 
often in other walks of life is the boon and the compensation of 
mediocrity, that Hall exercised a conservative influence in the 
terminology of the New York system. The names used by the 
New York geologists for the palzeozoic formations remain, and 
are now printed as indelibly in memory: as they are in books. 
They carry with them no euphonic distinction. They are not 
made educationally suggestive. They are eminently common- 
place, and their raison d’étre is absolutely obvious. Potsdam, 
Chazy, Calciferous, Black River, Trenton, Utica, Hudson River, 
Clinton, Medina, Niagara, and the rest are all place names 
easily understood, easily remembered, and have been easily 
applied to beds at localities most remote from all of them. 
Plain men like them, and scholars, have not replaced them by 
anything more refined. In this respect geology has both set 
and followed this example. 
It belonged to the logic of Hall’s mind and a certain original 
fixity of idea in him to combat Emmons’ Taconic System. He 
rejected the injection of a new series of horizons. It compli- 
cated matters, and Hall shrank from enigmas. He looked upon 
