Correspondence. 187 
ogists that the Ohio falls at Louisville have only been in existence 
since the ice age. The old channel of the Ohio river is supposed to 
have been south of its present bed where the city of Louisville now 
stands. While this may be true, perhaps, of one branch of it, yet 
another channel, as we will notice, has been discovered on the north 
side of the river in Indiana. The plain, upon which the city of Louis- 
ville is built, is chiefly a filled-in pre-glacial valley formed by the 
Beargrass and other tributaries that joined the Ohio at this place. 
Many of the smaller streams were entirely cut off during the melting 
of the ice-sheet, and the two branches of the Beargrass, still in exist- 
ence, are only relics of their former greatness, their mouths having 
been filled in to a very great extent. At the mouth of the East branch, 
at one of the distilleries, a well was sunk to the depth of four hundred 
feet without coming to rock ; yet near it, the present stream flows 
over limestone rock that comes very near the surface. At the mouth 
of the west branch of the Beargrass a sewer is being constructed to 
connect with it. For the distance of over half a mile, right in face 
of the ridge or terrace, no rock was reached at a depth of twenty-five 
feet, showing that the ancient valley must have been this wide. The 
present stream is very narrow — not more than thirty feet wide — and as 
it breaks through the ridge it flows eastward, seemingly up hill, for 
evidence of an old channel is seen running to the west where it must 
have connected with the Ohio river in preglacial times, below, not 
above the falls, as at present. The valleys of the Beargrass opened 
into the wider valley of the Ohio where a meeting of the waters takes 
place. The old channels running through this valley or plain can still 
be traced through the city of Louisville and vicinity by the numerous 
depressions between the river and the ridges. About six miles above 
the falls the Ohio river seems to have parted in early times, as here 
the valley begins to open out on both sides of the present stream. One 
arm, if not several, came down on the Kentucky side, another stretches 
out around the city of JeS"ersonville, Ind., and can be traced by a line 
of swampy depressions at the base of what is known as Walnut ridge, 
very much like the preglacial channel of the Mississippi river at 
Minneapolis and vicinity. This Indiana branch or old preglacial 
river, leaving the present channel of the Ohio below XJtica, curved to 
the left — as we look up the stream — and, bending southward again, it 
joined the Kentucky branch below the fails. 
The Indiana survey, 1874, page 176 in speaking of this region says : — 
"In the gravel or altered drift of this region are fonnd mastodon 
remains at as great a depth as thirty feet, which seems to indicate the 
situation of an old river or lake bed." 
The United States depot of supplies stands near the south margin of 
this depression, and the well for the engine-house is forty-four feet in 
depth, going through strata of clay, sand and gravel — coarse hard 
gravel overlying the rock to the depth of about six feet. The depres- 
sion seems to deepen towards the north as there is a difl"erence of over 
