402 The Ohio Naturalist. [Vol. IX, No. 2, 



alluvium, but usually the layer of cherty clay is quite thin, and 

 the rock is exposed in roadways, railroad cuts and brook beds. 

 The terrace front is steep and practically continuous rock outcrop. 

 The bluff to the east of the terrace contains Ohio shale which 

 has been seen in several ex])osures, and below it the Olentangy, 

 not exposed, but the drift cover above the shale is thick. 



In some places, this terrace consists of two steps more or less 

 definitely separated by a little scarp. There is rarely any flood 

 plain below it before the river. It consists of Delaware and 

 Columbus limestone, the former becoming very thin and finally 

 wanting at the south end. 



The most important cultural aspect of the terrace, no doubt, 

 is the opportunity it affords for quarrying the limestone. The 

 terrace front has been opened nearly its whole length, and one 

 considerable quarry has been started in its top. The old Smith 

 and Price quarry, several little old ones, and the present Casparis 

 and at least one other small quarry are to be found in the terrace. 

 Part of the terrace top is under cultivation every year, and a 

 small portion is devoted to golf links. The Pennsylvania rail- 

 road finds on it an easy grade from the flood plain in West 

 Columbus up to its bridge at Marble Cliff and across to the 

 undissected upland on the west side. 



Opposite the west end of Fifth Avenue, is a low rock terrace, 

 the present flood plain 400-500 feet wide and three-fourths mile 

 long. It stands about 15 feet above the river and bears much 

 alluvium especially along its water front so that rock is rarely 

 exposed. 



Farther south and on the west side of the Scioto along the 

 big turn toward the east, occurs the most southern rock terrace 

 of this river. It is more than a half mile in length, a hundred 

 yards in width, and stands 20 feet or more above the river. It 

 has been so many times opened for quanying and modified by 

 erosion that details of its surface form are difficult to obtain. The 

 T. and O. C. railroad swings across it, as also does the highway. 



A few more rock terraces were found along the Big Darby. 

 The first is two miles south of Georgesville on the west side, and 

 is about one-fourth by one-eighth mile in size with its top 20-25 

 feet above the river. This is the only one along the Darby 

 creek that is far above the water. 



For two miles south of the intersection of Big Darby with the 

 Columbus and Springfield electric line, a number of miniature 

 rock terraces occur, rising 5-20 feet above the water. This 

 stream has cut thru the drift mantle, but has only begun here and 

 there to cut into rock, hence, it is in a much less advanced stage 

 of terrace development than the two larger rivers. Its terraces 

 are not large, and are never far above the water; but it seems 

 probable that a time will come when the Big Darby will have so 



