98 NEW YORK STATE MUSEUM 



character, thickness and present-day distribution of the Cambrian 

 and Ordovician strata, the late Cambrian sea probably covered 

 some of the area of the Lake Placid quadrangle, and the mid- 

 Ordovician sea quite certainly covered some, or possibly most, or 

 all, of the area of the quadrangle. However extensive the Cam- 

 brian and Ordovician rocks may once have been, they have since 

 been completely removed by erosion from the area of the 

 quadrangle. 



At some time or times during the middle or late Paleozoic era 

 the whole Adirondack region, then largely mantled with Paleozoic 

 sediments, was raised well above sea level. Some of this upward 

 movement may have taken place at the time of the Taconic revolu- 

 tion (at the close of the Ordovician), though it is generally con- 

 sidered that the major uplift occurred at the time of the Appa- 

 lachian revolution (toward the close of the Paleozoic). In north- 

 ern New York this upward movement was not accompanied by 

 folding of the rocks, but there was a general tilting of the strata 

 downward toward the south or southwest. 



Mesozoic History 



The erosion cycle inaugurated by the Paleozoic elevation of 

 northern New York continued for a vast length of time, or till 

 late in the Mesozoic era or early in the Cenozoic era, when the 

 Paleozoic strata were largely removed from the Adirondack area 

 and another eroded surface approaching the condition of a pene- 

 plain was produced. This is commonly referred to as the Cre- 

 taceous peneplain. Apparently this peneplain was least perfectly 

 developed in the central and east-central Adirondack area, including 

 the area of the Lake Placid quadrangle, where various hard rock 

 masses (monadnocks) stood out more or less prominently above 

 the general level. This peneplain was upraised late in the Mesozoic 

 era or early in the Cenozoic era, and distinct remnants of it in 

 northern and central New York now lie at altitudes of from 2000 

 to 3000 feet or possibly more in some places. Within the quad- 

 rangle, however, no very accurate idea of this peneplain or its 

 remnants can be gained because it was only imperfectly developed 

 there. 



It is quite certain that much of the faulting which has so largely 

 influenced the major topographic features of the eastern and 

 southern Adirondacks took place after the production of the 

 so-called Cretaceous peneplain, and probably at the time of its 

 uplift. Some zones of fracture, however, like the Wilmington 



