ee 
he 
Natural Terraces and Ridges on Lake Erie. 37 
‘resting’on shales. In Erie County, on the line of the Mansfield 
railroad, it is composed of cliff limestone supporting black slate ; 
its base about 130, and its summit 180 feet. 
It will be interesting now to compare the elevations above 
given, for ridges in Western Ohio, with those of the great lakes 
_ in other states. In Michigan, at the east line of Washington 
couity east of Ann Arbor, is a well-defined ridge running nearly 
north and south, whose summit is 140 feet above Detroit River, 
De 
at Detroit. Around Monroe, in Wayne county, Michigan, are 
some irregular sand ridges, not more than thirty feet. They 
are also visible on the north shore of Lake Erie, in the flat coun- 
try between Erie and Huron; their elevation is not known, but 
they are apparently as high as 200 feet. 
Mr. Roy, a Canadian engineer, has made a section across the 
ridges back of ‘Toronto to Lake Simcoe, as reported by Mr. Lyell, 
and has given their respective elevations as follows: 
No. 1.—one mile north of Toronto, 20 to 30 feet high— 
base above Lake Ontario, . P : . 108 feet. 
No. 2,—24 miles from Toronto, 50 to 70 feet high— 
base above Lake Ontario, . ; ; . 208 
No. 3.—5 miles from lake—10 feet high—summit, 288 “ 
Five other ridges or terraces are given by Mr. Hall, in the ge- 
ology of the 4th district of New York ; also on the authority of 
Mr. Roy, referring apparently to the elevation of their base. 
“ 
No. 4.—above Lake Ontario, Cee 
No. 5. 66 6 é : : - : ec. tye 
No. 6. tc 6 tc : : : spit >: sides 
Bere re apr Gere wench hed dot tiggg ta 
No. 8. 6 e te ; ‘ . 762 * 
Mr. Lyell observed eleven ridges between the Lake and the 
summit for Lake Simcoe, the elevation of the eleventh, or last 
and highest, corresponding with No. 7, of the New York Report. 
The elevation of Lake Erie above Ontario is generally stated at 
332 feet, so that the three first ridges or terraces, in rear of 'To- 
Tonto, are below the surface of Lake Erie. 
_ Mr. Barrett, a New York engineer, furnished Mr. Hall with the 
height of some points on the Lockport ridge, south of Lake On- 
tatio and opposite Toronto. They are as follows: 
See Ota jC orctool ip Georgy ety 7-968 feet. 
Middleport, 10 miles east, . 8... ts 185 
Albion, Orleans county, : : : ‘ . 188 “g 
Broce. port, Monroe county, . : ; 3 . 188 44 
None of these correspond in height with those on the north 
Shore, as they should do if they were the result of littoral action 
