Table 2. Properties of basal 



till and flow 



till in study area. 





Basal 



till 



Flow till 



Color 



Olive gray Yellowish gray 



Olive gray Variegated 



Grain size 









(weight pet) 









sand 



22 



16 



7 13 



silt 



40 



39 



46 46 



clay 



38 



45 



47 41 



Natural 









(weight pet) 









water content 



16 



16 



21 20 



Unconf ined 









compressive 









strength (kg/cm^) 



1.8 



1.8 



0.7 0.9 



Shear strength 









(kg/cm2) 



0.7 



0.6 



0.3 0.4 



Atterberg limits 









liquid limit 



26.7 



1 



32.0 29.2 



plasticity index 



9.1 







11.8 10.4 



^No data. 



Two types of basal till were found in the cores. An olive-gray basal till 

 was found between Ashtabula and Fairport Harbor (cores 54, 55, 60, 61, and 70) 

 and between Avon Point and Huron (cores 77 to 80, 82, 86, 98, and 99); a 

 yellowish-gray basal till was found in the Lorain-Vermilion area (cores 84, 85, 

 92, 97, and 98). The yellowish-gray basal till overlies the olive-gray basal 

 till in core 98. 



Flow till is found in the Cleveland area and between Lorain and Huron (cores 

 71 to 76, 81, 82, 92, 95, 96, 98, 99, and 100). A nearly structureless olive- 

 gray flow till with minor pea gravel and reddish-brown clay pods was found in 

 the Cleveland area (cores 71 to 76). The flow till between Lorain and Vermilion 

 (cores 81, 92, 95, 96, 98, 99, and 100) has contorted flow banding and ranges in 

 color from olive gray to dark yellowish brown. This flow till overlies a basal 

 till in cores 92, 98, and 99. 



The basal till and flow till are exposed nearly continuously between 

 Fairport Harbor and Avon Point and between Lorain and Vermilion. Their surface 

 echo character on the seismic records ranges from smooth to irregular. In 

 general, the till in the Cleveland area has a smooth surface echo character 

 (Fig. 18); the till exposed both east and west has a more irregular surface 

 echo character (Fig. 19). 



The till surface from Conneaut to Fairport Harbor slopes lakeward at 2 to 

 4 meters per kilometer. Between Fairport Harbor and west Cleveland the slope 

 is gentler, 1 to 2 meters per kilometer. From west Cleveland to Avon Point 

 the slope is steeper but fairly uniform at 2 to 3 meters per kilometer. 



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