MAIN MORAINIC SYSTEM OF THE MIAMI LOBE. 369 



for tlie drift lias filled that whole region to a level above the tops of the 

 highest limestone ridges of the preglacial divides. The data concerning 

 the wells referred to are presented later, in connection with the discussion 

 of the region in which they occur. A well in St. Paris, 80 rods northwest 

 of the one reported above, stnick rock at 370 feet, but no data concerning 

 tlie character of the drift were obtained. 



At Tro}' the drift has a known variation from 50 to 133 feet in tliickness. 

 At New Carlisle a large amount of drift was penetrated, but the writer was 

 unable to learn its exact thickness and structure. The uplands north of 

 New Carlisle, for a distance of 10 miles or more, are thinly coated with 

 drift, and so also are those south of this village between Honey Creek and 

 Mad River. West of the Miami River, also, the drift is thin from Troy 

 southward to Dayton. Some of the wells west of Tippecanoe on the 

 uplands strike a dark-colored clay, perhaps a soil, just above the rock. In 

 Tippecanoe water wells penetrate 30 feet or more of till. Below Tippecanoe, 

 in the vicinity of Tadmor, there are lowland tracts along the Miami River, 

 where tributaries enter from the uplands, in which 50 to 75 feet of till is 

 exposed. 



The greater part Qf the city of Dayton stands on a gravel plain, but in 

 the portion west of the Miami, known as Dayton View, the drift has an 

 undulating surface, and, though mainly composed of gravel, has a capping of 

 till thickly set with bowlders. A gas-well boring near the corner of First 

 and Findlay streets penetrated 247 feet of drift, maiidy till. A well on the 

 waterworks grounds near Mad River, 225 feet in depth, did not reach the 

 rock. This penetrated clayey deposits (probably alluvial) for about 50 feet, 

 beneath which depth the drift was mainly gravel. The supply of water for 

 the city is obtained from a series of wells which barely enter the gravel 

 beneath the alluvial clays. At Osborne, a village on Mad River, a few 

 miles above Dayton, drift was penetrated to a depth of 207 feet, but its 

 structure was not learned. 



At Miamisburg a portion of the valley has rock near the level of the 

 river bed, but a gas- well boring made in that village penetrated 181 feet of 

 drift, mainly gravel. The deep portion of the valley lying below the level 

 of the stream here seems to be a narrow gorge. The valley above stream 

 level is somewhat constricted for 2 to 3 miles below Miamisburg, though it 

 IS probably of preglacial excavation. 



MON XLI 24 



