408 I. He. OGILVIE 
but the homogeneous character of the deposits surrounding 
them, and the entire absence of any indications of shore forma- 
tions or island character, point very strongly in this direction. 
No sediments are found later than the Utica slate until the post- 
glacial submergence caused the deposition of the Champlain 
clays. The region was, therefore, above the sea for an immense 
period of time and its erosion history isa hard one to read. The 
close of Ordovician time was the date of uplift ; the region was 
affected by the same movements which caused the Green moun- 
tain uplift. But whereas the Vermont region was subjected to 
great folding and metamorphism, in New York the effect was less 
pronounced and resulted in faulting only." 
These faults are the most conspicuous features of the present 
topography. They have caused numerous drainage adjustments 
and have produced most marked effects upon the whole subse- 
quent physiographic history. The faults run in general north- 
east-southwest directions, and were accompanied by block tilting 
towards the east. The drainage lines have placed themselves 
along the fault lines, and the tributaries on opposite sides work 
against an abrupt fault cliff, or a gentle tilted slope, respec- 
tively. Those with the slope for their course have a conspicuous 
advantage, and have extended their courses much farther back 
than those flowing in the opposite direction. Some of the above 
facts were brought out by Professor Brigham,? who noted on the 
maps that the southeastward flowing tributaries had much longer 
courses. 
Throughout the remainder of Paleozoic time the region was 
a land area, and very little trace of the sequence of events has 
been found. The time was long enough for many erosion 
cycles, but such evidence as there is points toward gentle simul- 
taneous erosion and uplift, perfect baselevel being at no time 
*H. P. CUSHING, ‘‘ Report on the Boundary between the Potsdam and Pre-Cam- 
brian rocks north of the Adirondacks,” Stxteenth Ann. Rept. N. Y. State Geologist, 
1896. i 
2“ Note on Trellised Drainage in the Adirondacks,” dm. Geo/., Vol. XXI (1898), 
p. 219. 
