GeoT Geography | Glacial Erratic Boulders | The Ultimate Erratic? | Ultimate Erratic -- Page 2 | Glacial Landforms -- 1 | Glacial Landforms -- 2 | Glacial Landforms -- 3 | Glacial Landforms -- 4 | Loess and Sand Dunes | Hoopeston's Location | Landscape of Northern Vermilion County | Penfield Illinois
The landscape of northern Vermilion County used to be very different than
the one we see today. A great deal of modification has been done by the
glaciers of the Pleistocene Epoch.
Prior to the glaciers, northern Vermilion County was much hillier and was
crossed by the Teays River and its valley. The Teays is believed to have
originated in West Virginia and flowed westward across Ohio, Indiana, and Illinois to join the
ancestral Mississippi southeast of present-day Peoria. In northern Vermilion County this river cut a
valley nearly 400 feet deep. As glaciations progressed, this valley was
eventually filled with glacial drift and is no longer visible at the
surface. Deposits of sand and gravel in it are an important source of groundwater for cities and
towns located above it. Like, Hoopeston.
In the latter stages of the Ice Age, a glacial ice front paused just north
of Hoopeston. For many years the ice front melted as the glacier continued
to flow to this point. A ridge of glacial till was built up all along this
melting margin of the glacier. This ridge can be traced well into Indiana,
and to the northwest in Illinois. It is known as the Chatsworth moraine.
But the glacier did more than just build a ridge. It also made a lake. As
the ice front retreated, the water released was trapped between the
glacier to the north and the Chatworth moraine to the south. The resulting pool of
water is known as Lake Watseka. Much of the flat land over Iroquois county
is the floor of this glacial lake. The lake floor was further smoothed by wave
action distributing sediments.
Eventually, Lake Watseka filled with water to the top of the Chatsworth
moraine. Water then poured over the moraine at 3 or possibly 4 locations and partially
drained the lake. Three of these lake outlets pass through the Hoopeston area. One is located in the north central and western part of town along 6th avenue, 2 more are located west of Illinois Route 1, still another is approximately 3 miles farther west.
Thomas Hoopes, one of the original landowners in northern Vermilion County
suggested to surveyors appraising a route for a railroad that lower land
lay to the west. They were surveying a route which would cross the
Chatsworth moraine. Mr. Hoopes suggested the lower route using one of the
lake outlet channels. The railroad located the line in this more level
outlet. When a second east-west railroad was built the site for the town was determined. Hoopeston is therefore located several miles west of where it would have been!
Today, the outlet channels continue in importance as a level route not only
for the railroad but also a state highway through the moraines of northern
Farther south, the water drained from Lake Watseka cut through the Gifford
and Newtown moraines north of Danville. A dam built on the North Fork of
the Vermilion river created Lake Vermilion, the primary water source for
Action by geologic processes in the past continue to have an impact on life
in northern Vermilion county today. From glaciers and moraines to lakes
and valleys, the pattern of life as we see it today has been affected by
landscape development in the past. And, glaciers are an important reason
for the changes.
See the wide white area between the contour lines north of town? That is one of the lake outlets. Look to the north and see the relatively flat floor of glacial lake Watseka. Another lake outlet appears as the white area to the west of the city, and the third is located farther south in front of the moraine. All three outlets joined just south of Hoopeston and the lake waters then drained toward the present-day Vermilion River at Danville.
Pleistocene Glaciers & Groundwater
Pleistocene Glaciers and Groundwater
Guest Column by GeoT
The Pleistocene was the time of the great Ice Age of the world. The glaciers were most extensive in the Northern Hemisphere, but they also existed in the southern parts of South America, the mountains of southeastern Australia, and South Island New Zealand as well.
Global temperatures cooled an estimated 7 to 13 degrees Fahrenheit, resulting in an accumulation of ice in certain continental and mountain areas. The reason for the cooling is a subject of much debate, but this much we know: there were at least four and possibly as many as fourteen Ice Ages separated by times of warmer climate called interglacials - ancient global warming. During such times, glaciers melted, soils formed, and vegetation grew, only to be covered by subsequent glacial advances when the climate cooled again. All of this is known or suggested through the study of the glacial stratigraphy by the geological surveys of various Midwestern states.
It is also known that the glaciers were great modifiers of landscape. The ice accumulation centers in North America, near Hudson Bay, repeatedly sent ice outward in all directions, and severely eroded the Canadian Shield in the process. Additionally, the basins of the Great Lakes of North America were produced by the erosive action of the ice.
What the glaciers erode from one place comes to rest someplace else, and existing landscapes in the latter areas were modified too.
Prior to the glaciers, stream drainage was well established in the Central Lowland. One river, the Teays, (known in Illinois as the Mahomet or Mahomet-Teays) had produced a valley from the Blue Ridge of North Carolina to the southern part of Illinois, where it emptied into an extension of the Gulf of Mexico.
The ancestral Mississippi River entered Illinois from the northwest and flowed southeastward to meet the Teays. The two rivers joined southeast of present-day Peoria. That ancient Mississippi River was a tributary of the Teays. Subsequent deposition by various glaciers filled this part of the Mississippi valley and forced it to its present location along Illinois' western boundary.
Glacial deposits also filled the Teays valley system. (Some sections of the valley are still visible in the unglaciated areas of the Appalachians.) Floods of sediment-laden meltwater coursed down the Teays and its tributary valleys filling them with sand, gravel, and associated material. Later glaciers overrode the entire complex, covering it with layers of glacial drift, leaving end moraine and ground moraine as the surface. The pre-glacial system of valleys was totally obscured.
Today, the layers of sand and gravel in the Teays valley system are an important source of clean, abundant, groundwater. Many towns and cities along this preglacial valley use this resource as their municipal water supply.
As clean water becomes an increasingly precious resource, surely, places located above this preglacial feature will find it to be of utmost economic importance.
There may be hope for my small town in eastern Illinois yet!