128 J- ERNEST CARMAN Vol. XXII, No. 5 



introduced glacial deposits extend, but their presence at 15 

 feet below the surface and the calcite filling at greater depth 

 show that the region was higher and the ground water surface 

 deeper at the time of the formation of the cavernous zone and 

 probably at the time when the gravels were carried down the 

 passages on a general five degree gradient. The clay on the 

 other hand gives evidence that the channels were filled with 

 water at the time of the clay deposition. This indicates a 

 higher water table, or deposition at the time that the region 

 lay beneath Lake Maumee and its successors. The general 

 similarity of these clays to the clay deposits of the old lake 

 bottom adds support to this latter interpretation. As the 

 waters of the lake bottom at this place were agitated, the fine 

 silt settled down into the water of the channels beneath, which 

 were more or less connected with the lake, and in these channels 

 and the connected rock cavities the clay deposition took place. 



Two miles north of Silica a quarry, exposing the same 

 horizons as at Silica, shows this same cavernous zone with 

 crystal lined cavities. A fine grained clay was observed in 

 the cavities at eight feet below the rock surface and a workman 

 reported that they had found some very tough and sticky 

 clay in the cavities of this zone at 15 feet below the rock surface. 

 This clay is undoubtedly of the same type and origin as that at 

 Silica. 



Considerable masses of tough, fine grained clay were seen 

 associated with the loose blocks of stone on the quarry faces at 

 the Holland quarry, seven miles south of Silica and at the 

 France Stone Company quarry, one mile south of Monroe, 

 Michigan. The clay was much like that seen at Silica, but in 

 neither of these places could it be so definitely connected with a 

 glacial origin. 



