1884.) The Theory of a Glacial Dam at Cincinnati, ete. 565 
Upon seeing this report, Professor I. C. White, of Morgantown, 
West Va., situated in'the Monongahela valley, and who has for 
many years been an active member of the Pennsylvania Geologi- 
cal Survey, informed me that the ice dam at Cincinnati was 
exactly what was needed to explain the terraces along the Mo- 
nongahela. It appears that from Pittsburgh as far south as Fair- 
mount, in West Virginia, a distance of 130 miles (which was as 
far south as Professor White had examined), the valley of the 
Monongahela shows signs along its edges of having been par- 
tially silted up with heaps of trash, such as clay, sand, gravel, 
boulders, drifted logs and other rubbish, brought in by its tribu- 
laries from higher land. The striking peculiarity of these terrace 
deposits is, that they “ suddenly disappear at an elevation of 1050 
% 1075 feet above tide; not a single rounded and transported 
boulder ever being found above that latter horizon, though occur- 
ing in countless numbers below this level. The hills above the 
"iver often rise three hundred or four hundred feet higher than 
the upper limits of the deposits, so that there can be no mistake 
about the elevation at which the terrace deposits disappear. * * 
k from the channel of the river, especially where the surface 
Configuration would make quiet water, there occur thick deposits 
of very fine, bluish-white clay in which great numbers of leaves 
are most beautifully preserved. This deposit is purest near the 
aver limits of the terraces. | 
In the vicinity of Morgantown terraces of transported mate- 
ocur at the following approximate (measured by barometer) 
First B Feet T Feet pone tide, 
š aat tiiit a a 75 865 
aga 175 965 
Fifth ik ec fie vins bi acne «<0 2p 200 990 
275 1065.” 
À ie Saag of the fifth terrace in this series are frequently 
Tn such inland from the Monongahela on the tributary streams. 
ing ee deposit near Morgantown, called the Flats, and cover- 
Eey; or four square miles, wells have been sunk sixty-five 
a aoa bed rock. This is 275 feet above the river 
i Other above tide, 
White « tributaries of the Monongahela, along which Professor 
oO has noted the clay and other deposits of the fifth terrace, 
