SURFACE GEOLOGY. 



61 



or two intermediate ones. Here, as west of the Cuyahoga, the north or 

 lowest ridge, about 100 feet above the Lake, and another which corre- 

 sponds to the south or highest ridge of the country west of Cleveland, 

 and which has an elevation of about 200 feet, are the most constant. I 

 give below two profile sections of the lake ridges in Lake and Ashtabula 

 counties, taken from the reports of Mr. M. C. Read. 



Lake Ridges, Ashtabula County. 



«. Drift clay. 



h. Erie shale. 



In explanation of the above profile Mr. Read says : " A and B repre- 

 sent the two continuous lake ridges, averaging in Ashtabula county about 

 one mile apart. The spaces between them and between the north ridge 

 and the Lake present to the eye the appearance of level terraces, but they 

 slope gradually toward the Lake. The records of icebergs in the old 

 lake, at comparatively recent epochs, are left in the granite bowlders 

 scattered along the north slope — most abundant on the slope of the 

 northern ridge." The following sections of the south ridge, taken by 

 Mr. Read, give an interesting view of its structure : 



PROFILE SECTION OP SOUTH EIDGE, ASHTABULA COUNTY. 



The summit of the ridge at this place is 202 feet above the Lake. No. 

 1 of the section is composed of water-washed sand and loam, from 4 to 6 

 feet thick, the maximum thickness being south of the crest of the ridge, 

 where the sand is stratified in billowy lines, evidently carried by the 

 wind from the old beach on the opposite side. No. 2 is yellow clay, and 

 No. 4 blue clay, the first varying in thickness from to 12 feet, the 

 latter 20 feet thick to the railroad track. Both these deposits of clay are 

 unstratified, and are filled with fragments of the local rocks, with many 

 striated pebbles of metamorphic rock, and no water-worn pebbles or bowl- 

 ders. No. 3 is an old swamp, containing fragments of coniferous wood, 

 the earth deeply stained with iron, and in places containing bog iron ore 

 at the bottom, the whole now covered with drifted sand. In the opinion 



