Great Ice- Dams. — Taylor. 29 
made up of several beaches close together; on the thumb in 
Michigan it nearly always presents a dual form, one ridge 
being about ten feet above the other. Its ridges in Ohio cover 
the interval from about 90 feet down to 65 feet above lake Erie. 
On entering New York it begins to rise somewhat in altitude, 
and it changes in the same way northward on the thumb. At 
their first halt the ice-dams of lake Warren stood at the Alcona 
and Hamburg moraines. It seems certain that no change of 
lake level or outlet occurred until after the next halt, when the 
dams stood on the Hagenville and Alden moraines, for Mr. 
Leverett found the upper member of the Forest beach extend- 
ing as far as Alden. The remainder of the history of lake War- 
ren has not been worked out, except as to the location of two 
moraines in New York and the place of its eastward outlet at 
its closing stage. According to Prof. Fairchild, the lower 
member of the Forest beach has been traced from north of 
Indian Falls, N. Y., eastward along the north or inner side of 
the Lockport moraine to Lima.* 
On the hills south of Syracuse are the magnificent aban- 
doned canyons and waterfalls which were discovered three or 
four years ago by Mr. Gilbert. They were made by a great 
river flowing eastward and the head levels of the upper ones 
are suggestively near the level of the plane of the Forest beach 
produced. From the relations of the moraines and beaches it 
seems clear that these outlets could not have been open while 
the ice-front stood on the Lockport moraine. For Indian Falls 
and Batavia are towards the end of the lobe and Syracuse is far 
back on its side, so that the margin of the ice must have been 
higher at Syracuse than at Batavia. Hence it seems probable. 
as the only alternative, that the Albion ice-dam stood with its 
front resting on the hills south of Syracuse when the eastward 
outlet was first opened close along its foot, and that it was 
during its stand there and during the early steps of its retreat 
from that position that all those channel features were made. 
applied the name "Crittenden." It seems certain that the two are in 
reality the same beach. Latterly, Prof. Fairchild and others have 
sometimes designated this beach as the "Warren shoreline." Spencer 
originally afjlied the name "Lake Warren" to supposed extensive high 
level waters, whose existence, however, has not been establishd. The 
present mort restrictd application of the name was suggested by the 
writer in 1896. (Bull. G. S. A., vol. 8, 1896, pp. 56-57.) 
*Lake Warren Shorelines in Western New York and the Geneva 
Beach." Bull. G. S. A., vol. 8, 1896, plate 30. 
