The natural beauty of the Illinois River-with its broad valley and high bluffs-inspires artists, writers, poets, and politicians. Hedley Waycott and numerous others painted the landscape from Grandview Drive, author Jerry Klein describes upper Peoria Lake as "one of Illinois' scenic wonders and recreational treasures," and poet Byron DeHaan beholds "a heart-stopping valley" from the vantage former president Teddy Roosevelt proclaimed the "world's most beautiful drive."
The artfulness of the landscape bespeaks the legacy of the glaciers; the power of the shifting ancient Mississippi River; and the underlay of sandstone, limestone, shale, and coal long studied by geologists.
This May begins the centennial of the Illinois State Geological Survey (ISGS) in its modern form. As one of the first events in the year-long celebration, ISGS hosts the 51st meeting of Midwest Friends of the Pleistocene. They'll examine the ancient Mississippi and Illinois rivers and new geologic mapping of the middle Illinois River Valley.
In 1897, Frank Leverett, a pioneering glacial geologist, recognized a section of Farm Creek (now within the Farmdale Reservoir) in Tazewell County for its graphic record of multiple glaciations. The site spans nearly 65,000 years of the Pleistocene Epoch of the Quaternary Period (Ice Age). Studies there gave name to broad geologic concepts and earned it a place on the National Register of Significant Geological Places.
The reconstruction of Interstate 74 through downtown Peoria has dramatically shown various layers of glacial outwash underlying the valley from Perry Street to the river. In fact, extensive deposits of sand and gravel underlie the Illinois Valley and its tributaries. Gravel pits on both sides of the river, from Bureau and Chillicothe to Spring Bay and Pekin, testify to this glacial heritage. A particularly thick layer of sand became evident in the cut for the reconstruction of Peoria's Monroe Street Bridge. From there down to the river, gravel and sand predominate, with occasional larger rocks. On the East Peoria side near routes 116 and 74, and Fondulac Drive, a layer of coal several feet thick became obvious. Thick lake clay, silt, and glacial sand and gravel form multiple layers under the soils of wind-blown silt (loess) and dune sand, riverine deposits, and glacial till. Large boulders known as glacial erratics can still be found along hillsides and ravines.
An 1851 law authorizing a geological survey of Illinois mandated "a search for and examination of all the beds and deposits of ores, coals, clays, marls, rocks and such other mineral deposits as may present themselves." The surveyor was to make annual reports, maps, drawings, furnish specimens to all institutions of learning in the state, and produce a geological map of the state. Amos Worthen became director of this survey, and eight volumes of the Geological Survey of Illinois were published between 1866 and 1890.
Worthen visited Peoria County in 1859, but his report wasn't included until Volume V of the survey was published in 1873. He noted terraces of sand and gravel, rising from 30 to 50 feet above the low water level of the river. He remarked about the remains of a mammoth-two molar teeth and a portion of a jaw-found in a Peoria bluff. He observed "bold escarpments" of sandstone-steep cliffs along Kickapoo Creek Road near Bartonville that still offer a scenic surprise.
Native Americans fashioned clay into pottery. Worthen commented on the excellent brick clay and the "inexhaustible supply of sand and clean gravel." "All the railroads in the state might obtain here an ample supply of ballast for their roadbeds, without greatly diminishing the amount of this material to be found in this county," he wrote.
Limestone was already being quarried, creating such enduring landmarks as the 1844 stone church-Christ Church-in Limestone Township, as well as stone homes and schools. Stone for foundations, wells, pavement, and buildings came from various local sites.
Marquette and Joliet noted coal outcrops near present-day Creve Coeur. Worthen also visited and collected data from coal mines on both sides of the river. He commented that seams of coal had been worked since the earliest settlement of the county. The mines at what's now Kingston Mines were among the first opened for supplying coal to the river steamers, he noted. He considered Peoria County one of the most important coal-producing sections in the state. In Jubilee Township, he noted fossil wood fragments two to three feet long-"so large as to require the strength of two stout men to load them into a wagon."
In all, a rich legacy from billions of years still is being seen and studied today. AA!