266 New York State Museum 



foundland into New York State, entering from the north- 

 east. In this trough thick formations of graptolite shales 

 were deposited. The Upper Canadian beds are found in 

 the Ottawa valley and in the south they have been found 

 at intervals in southeastern New York (Wappinger ter- 

 rane), New Jersey and Pennsylvania, in the last-named 

 state having a thickness of 2000 to about 4000 feet. The 

 strata of Beekmantown age in New York have an aggre- 

 gate thickness of 1500 to 2000 feet. At the end of Beek- 

 mantown time uplift and withdrawal of the sea produced 

 the unconformity between the Beekmantown (Canadian) 

 and the Chazy (Lower Ordovician). (Figures 29, 30.) 

 There is no positive evidence that the entire Adiron- 

 dack area was ever submerged during Ordovician times, 

 so the central Adirondacks must have persisted as an 

 island in the Ordovician sea. There were a number of 

 oscillations through the period bringing the land around 

 the island now above sea level, again below, but it is not 

 necessary to enter into that here. Except for this island 

 formed by the Adirondacks and the alternating condi- 

 tions in its vicinity, New York State was entirely or al- 

 most entirely submerged practically throughout Ordo- 

 vician time after the Chazyan (Lower Ordovician). 

 Some even believe that the Middle Ordovician (Trenton) 

 sea submerged the entire Adirondack area. During this 

 time the prominent land masses were the land mass of 

 Appalachia to the east and another to the north in the 

 Hudson Bay region of Canada. Limestones characterize 

 the earlier Ordovician deposits in the state not because 

 the water had great depth or was far away, but because 

 the neighboring lands were of low relief and there was 

 little clastic material carried by the streams. During the 

 latter part of the period the lands were higher, erosion 



