168 



heavy growth of elm, hemlock and ash, with some maple and 

 beech. This elevated ground is the summit level, from which 

 the waters flow in opposite directions, into Lake Ontario on the 

 north, and into the Clyde river, and thence into the Cayuga and 

 Seneca lake outlets on the south. The country probably then 

 formed an estuary through which water flowed into Lake Onta- 

 rio, which was then probably at an elevation of 150-200 feet 

 higher than at present. 



A section at this place, and at numerous others near the same 

 spot, presents the following characters : 



1. Muck, or vegetable soil, supporting a heavy growth of tim- 

 ber, two feet or more in thickness. 



2. Fine sand, with occasional thin bands of clay, often consist- 

 ing of alternating layers of sand, twigs, leaves and other frag- 

 ments of vegetable matter, and much blackened thereby ; two to 

 three feet thick. 



3. Muck, or peaty soil, composed of decayed fragments of 

 wood, bark, leaves, &c., enclosing trunks of trees of large size, 

 about four feet thick. 



Skull of Castoeoides Ohioensis. 



4. Fine sand, with shells of Planorbis, Valvata, Cyclas, &c., 

 one to two or three feet thick. 



5. Ancient drift, with northern bowlders and fragments of the 

 sandstones and limestones, which occur in place a few miles far- 

 ther north — depth unknown. 



The thickness of 2, 3, and 4, is variable, though the bottom of 

 No. 3 usually varies little from the depth of eight feet from the 

 surface. A glance at the section reveals the true period of the 

 deposit, showing conclusively that the whole is a lacustrine form- 

 ation, made subsequent to the deposition of the ancient drift, 

 (No. 5,) which is characterized by its foreign materials, while in 

 the later deposit not a pebble of the size of a pea can be found. 



The fossil is doubtless of the same age as the remains of the 

 mastodon. These are all found in situations showing that this 

 period was subsequent to that when the earth has undergone any 

 great change. 



Its geographical distribution must have been extensive, as it 

 has been found in Ohio, and lately at Natchez. 



