76 NEW YORK STATE MUSEUM 
In western New York and over the region of the present Lake 
Ontario, the hard and soft early Paleozoic strata outcropped along 
a nearly east and west direction, and hence considerable streams, 
tributary to the major southwestward flowing streams, doubtless 
followed the belts of soft (shale) rocks. Such a west-flowing 
‘stream may have followed the belt of weak Ordovicic shales which 
runs under the present Lake Ontario. 
In southeastern New York, in the midst of the Mesozoic era, the 
land was lower than at the beginning of the era as shown by the 
fact that the late Cretacic sea spread over at least some of the 
region. This gave a better opportunity for the development of an 
eastward or southward drainage toward the Atlantic basin, and at 
this time it 1s possible that the ancestors of the modern Hudson, 
Delaware, and Susquehanna rivers were formed. 
However uncertain our ideas may be regarding the topography 
and drainage of the early and middle Mesozoic, we are nevertheless 
sure that by the close of the period the topography of the State was 
that of almost a peneplain which has already been described, and 
that the streams were all of low gradient and very sluggish. During 
the long erosion time of the Mesozoic, there must have been many 
changes in stream courses and adjustments to rock structures. By 
the close of the era the courses of the rivers are, as yet, not defi- 
nitely known, though in accordance with the above discussion we 
are reasonably certain that the principal drainage of the State from 
the northern, central, and western portions was southwestward to _ 
westward into the Mississippi basin, while the drainage of the 
southeastern portion was southward to southeastward into the 
Atlantic basin. 2 
