MAIN MORAINIC SYSTEM OF THE SCIOTO LOBE. 399 



northeast from this village for a distance of about 3 miles. The ridges are 

 somewhat disjointed, but at least two well-defined chains exist. These ridges 

 terminate abruptly, but at the northern end of the eastern one is a network 

 of lower ridges, inclosing a small lake. From here the inner (eastern) 

 border of the moraine is shifted 2 miles or more westward, there being a very 

 flat tract toward the north. The moraine west of the plane tract just noted 

 consists of a massive ridge with north-south trend, which has on its crest and 

 slopes a series of knolls and ridges of varying shape, size, and degree of 

 sharpness. Tlie highest rise 30 to 40 feet above their immediate borders, 

 but the ridge on which they are situated has also some variation in altitude, 

 so that in following the crest oscillations of 150 feet or more are in places 

 made within a distance of 2 miles. From the passes, or lower portions of 

 the ridge, gravel plains lead westward into Mad River and Buck Creek val- 

 leys, joining the main stream that drained the Scioto and Miami lobes. The 

 most prominent of these tributary gravel streams noted are the following, 

 beginning at the south: (1) On a tributary of Buck Creek, through which 

 the Big Four Railway passes from Mechanicsburg to Catawba station; (2) 

 on a tributary of Buck Creek west and north of Mutual; (3) on a tributary 

 of Mad River from Cables westward; (4) on a tributary of Mad River from 

 Mingo westward; (5) on Mackocheek Creek; (6) Mormon Bottoms, east of 

 Zanesfield; (7) Hadley Bottoms, northeast of Zanesfield. 



In each of these tributary plains there appears to have been an out- 

 wash of gravel from the ice sheet, and an escape of waters to the Mad River 

 plain. From the crest of the moraine, which forms the water parting in 

 these passes, there was vigorous drainage westward, producing a flat- 

 bottomed valley, while eastward the streams flow among morainic swells 

 until they reach the till plain east of the moraine. This district afiFords 

 excellent opportunities for studying the phenomena of glacial drainage as 

 well as of glacial deposition. 



STRUCTURE AND THICKNESS OF THE DRIFT. 



A comparison of numerous slight exposures, such as the region affords, 

 makes evident the fact that the sharply morainic tracts have a larger pro- 

 portion of assorted material than have those with subdued expression. The 

 knolls which are composed entirely of till have usually gentle slopes. 

 Those which contain gravel and sand with the till may have gentle slopes 



