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Beaver Valley Before the Ice Age

Milestones Vol 25. No. 1

By Denver L. Walton

We've been talking, from time to time, about the history of the Beaver Valley and of the region which was known for many years to the English colonists as the "Ohio Country."

But the history of this little piece of the earth's crust which we call home didn't start with the Colonial period, nor with the "prehistoric" residents of the valley, the mysterious early Indian civilization whose people left many relics from the period of their occupancy of the area but disappeared entirely with a trace. No, the history of the "Ohio Country" goes back a few years before that.

We might as well start at the beginning.

The little piece of the earth's crust that is called Beaver Valley can trace its history back some 300 million years. At that time, the various layers of rock which make up our hills were being laid down as sediments. All of the rock exposed or detected by drilling or mining in Beaver Valley was deposited over a period of 100 million years or so.

The source materials for the rock came from different places, and some may surprise you. At different times, the land that was to become Beaver Valley was completely submerged, under shallow seas. At other times it was a flood plain, bordering a vast river. Each layer of coal is the petrified remains of steaming tropical jungle, some enduring for hundreds of thousand of years, with trees like giant ferns, vastly different from the forests of today.

Our limestone deposits are proof of repeated flooding by the sea, for limestone is composed of the fossil shells of countless tiny sea animals. The massive layers of sandstone which have been quarried for years as a source of building materials were deposited by raging rivers or by the pounding surf on a lonely beach and the shale and clay are evidence of eons of flooding by sediment-laden rivers, eroding away huge mountains to the east.

Yes, mountains to the east, but not the Alleghenies or the Appalachians, for these mountains are formed of folds in the same type of rock that is found in Beaver Valley, so they must have been formed later. And not the Blue Ridge, vastly older rock, but again, exposed later than the formation of our local rock deposits.

Geologists believe today that the sediments covering the Mississippi Basin, including present-day Beaver County, were formed by erosion of massive mountain ranges, whose roots would be located today in Europe! And this was possible because, during the Carboniferous Era (named for the coal deposits), there was no Atlantic Ocean, and the continents of North America and Eurasia were one! I told you it would surprise you.

The entire science of geology has been turned upside down in the last 30 to 35 years, as undeniable proof was finally accepted of the old, old theory of floating continents. If this intrigues you, read the Jan., 1973 issue of National Geographic, and you'll be convinced. -

The face of Beaver Valley has changed many times. The most recent drastic alteration, prior to that wrought by man, happened some 15,000 years ago, in the time of the last great glacier. This tremendous mass of ice flowed like a river because of its incredible weight. It eventually covered Northwestern Pennsylvania, and came down as far as the NW corner of Beaver County (from South Beaver to Ellwood City).

The glacier shaved off hilltops and filled valleys with sand, gravel and boulders. But the most significant change was the effect on the rivers, which did not follow their present courses, but flowed north, into the great lakes.

Lest I confuse you, glance at your road map of Pennsylvania. Locate the Monongahela River below Pittsburgh, and trace it north past the Point, where it becomes the Ohio, north into Beaver County, north to Rochester, then north up the Beaver River Valley to New Castle, up the Mahoning Valley (switch to an Ohio map), north to the Grand River Valley, and still north, to Lake Erie. This was the primary drainage pattern prior to the Wisconsin glacier.

Now find Steubenville on the map, and trace another stream north through the Ohio Valley, north at Liverpool through the Little Beaver Valley, then northeast from the Little Beaver near New Galilee to the Big Beaver Valley near Moravia. That was a tributary. Now put your finger over the Ohio River from Beaver to Liverpool, because 15,000 years ago, there wasn't any river there.

When the glacier moved down from the north, all of these north-flowing streams were dammed up, their outlets completely blocked. The first thing that happened was the formation of a huge lake (known today as Lake Monongahela). And as the water backed up further and further, it eventually spilled over a ridge into another watershed, and as water will, found its way to the sea by a new course. In doing so locally, it meant cutting a new channel westward through Beaver County, flowing upstream (south) through the present north flowing Ohio Valley south of Liverpool (better read that again); then crossing another divide to join up with the early river which occupied the lower Ohio Valley.

And if you think this is incredible, I'd better not mention how the Allegheny River came to be. (But I will.) Before the glaciers, it was three separate streams. The northern part, near Warren, flowed into Lake Erie through Lake Chatauqua. The central part, including the Clarion River, flowed in reverse up the French Creek Valley and this into Lake Erie. The southern part, including the Kiskiminetas followed its present course, meeting the Monongahela at Pittsburgh to form the Ohio.

You don't have to take my word for any of this, but read the whole story in the Topographic and Geologic Atlas of Pennsylvania, New Castle Quadrangle. If you still don't believe it, forget it. But wiser heads than ours claim that it happened that way.