Over the course of the planet's 3.5 billion-year history, eight supercontinents (see list of the major supercontinents below) have formed and broken up, a result of the churning and circulation in the Earth's mantle, which makes up most of the planet's volume. The breakup and formation of supercontinents has dramatically altered the planet's history.
The hypothetical supercontinent called Pangaea (ancient Greek meaning "all lands") was assembled from earlier continental units approximately 335 million years ago and began to break apart during the Triassic Period (250,000,000 BC - 205,000,000 BC) and the Jurassic Period (205,000,000 BC to 135,000,000 BC).
In fact, today's Illinois was south of Earth's equator twice! It was during these times that it was covered with tropical forests which over the millennia formed coal deposits. Some of the Mazon Creek fossils discovered in Illinois are found nowhere else in the world, like the "Tully Monster." Some ancient life represented are ferns, insects, shrimp, jellyfish and fish scales - fossilized in rock 310,000,000 to 200,000,000 million years ago before continents moved together to form Pangaea in the Paleozoic era.
From Pangaea to the Modern Continents.
Over 260,000,000 million years ago a shallow ocean covered the area, forming layers of limestone from the calcium carbonate shells of abundant snails, clams and other sea life. Fossils of trilobites, mollusks, sponges, corals, and crinoids can easily be found in the local laminar limestone deposits. Shark teeth and starfish have also been discovered here. An amateur paleontologist from Eyler, just east of Pontiac, found two new fossil crinoid species in Wagner Quarry south of Pontiac. Her husband, also a crinoid expert, named one of the new species pontiacensis, and the other Christinae, after his wife.
Through the Ice Age, there was a mile high block of ice atop the landscape. When it melted, Lake Ancona formed in where is now east-central Illinois with a clean sand bottom. It eventually drained and many smaller lakes were formed. As the climate became drier, Ice Age megafauna moved in. Local finds of wooly mammoth tusks and teeth, along with a 50-pound copper nugget transplanted by the ice from the Mesabi Range iron ore area of northern Minnesota. Buffalo (American Bison) covered the area during the Pleistocene Era (aka: as the Ice Age - 2.6 million to 11,700 years ago), and again 500 to 300 years ago, only to finally disappear in the early 1800s.
Bison bones were found along the banks of the Vermilion River in the area in 2011. They were only the third discovery of bison bones east of the Mississippi River from the Holocene Era, (12,000 years ago to present day), indicating only sparse, intermittent perhaps, distribution of the bison in this area then. The other two Holocene discoveries were near Ottawa in a silica quarry, and Mapleton, 12 miles downstream from Peoria, where the mouth of a tributary stream emptied bison carcasses into the Illinois River.
About 14,000 years ago the first humans (the original indigenous people) arrived. Only a few of their early spear points (Clovis points) have been found in Illinois which were lost in hunting these large game mammals. The Archaic Period peoples (8,000 BC to 1,000 BC) were wandering hunter groups, following game. Living in small groups, they roamed in search of food, camping several days to several weeks, and then moving on. They produced spearheads commonly found along rivers, creeks and out on the prairie. These artifacts we see today were made from flint and chert; a form of metamorphosed limestone, deposits of which are rare in this area. Some of their weapons and tools also include copper spear points from the Old Copper Culture (4000 BC to 1000 BC). A 6-inch copper point was found by Dwight, Illinois. The Archaic people found rare copper nuggets dropped here by retreating glaciers they hammered out into tools and weapons.
The Woodland Period (1000 BC to 1000 AD) saw more advanced cultures of settled groups in villages with gardens of sunflowers, squash, pumpkins, and beans to supplement hunting for game. Trade routes to Florida, Michigan, North Dakota, and other far-flung states were established for obtaining scarce items such as suitable stone for tools and weapons, copper for axes, and mica from Carolina for mixing with clay for stronger pottery. Workable stone from neighboring states like Indiana, obsidian (lava glass) from Wyoming, and copper from Minnesota and Wisconsin are evidence of that trading in Illinois. About 3,000 years ago pottery first appeared in North America. That crude early pottery has been found here. Other finds include bear teeth and elk antlers - both species have disappeared from the area long ago.
John McGregor, a Pontiac native who became the Director of the Illinois State Museum, found a blade that he determined was made by the same person who made the Mackinaw Cache blades found in Tazewell County, a group of blades widely recognized as the finest examples of “chipped” stone ever found in North America. He was involved in many of the early archaeological efforts in the state. He directed the Washburn, Illinois, excavation of a mass burial near a creek that contained four pits with approximately 200 individuals each!
The Mississippian Period (800 AD to 1600 AD) saw an even higher level of culture develop in North America. Instead of isolated sustenance gardeners and gatherers, maize (corn) was more widely introduced, planted in larger tracts, and still remains today as the dominant driver of our county’s culture and economy. Two flint hoes 11 inches long were found at two different locations along Rooks Creek as well as a cache of 26 hoes south of Pontiac. Simpler hoes from this time are found throughout the area. The use of these hoes marked the beginning of agriculture as we know it today.
The Mississippian people began using corn as their main community resource, rather than just another private family garden staple. Cahokia points are found here named after the Cahokia Mounds complex near Collinsville, which contains the largest prehistoric earthen structure in the Americas; Monk’s Mound. Larger at its base than Egypt’s Great Pyramid, Monk‘s Mound was the home of the Chief of what was at the time the largest city in the Americas.
|Indian drinking vessels found near Cahokia, Illinois.|
Nearly all the information we have of the prehistoric native human inhabitants of the area comes from discoveries of what they left behind; burials, tools, and weapons buried campsites and villages, and earthen works like Monk’s Mound in Cahokia. Burial mounds were common all over the state of Illinois, mostly by rivers, streams and other bodies of water.
Most mounds in Illinois are gone now, succumbed to tilling the soil for farming, treasure hunters and looters. In the early twentieth century, a banker named Payne from Springfield excavated the Billet Road mounds and stripped them of all their manmade items; now lost history. A mound north of Fairbury along the river was excavated while digging a basement for a house. It contained one individual and burial goods.
Unlike their counterparts who moved south to settle Central and South America, North America indigenous people produced no written language. Other than petroglyphs, or picture art (example 1 - example 2), that depicted events, surreal imagery, and early art, no translatable written record was left us. Names of individuals, their tribal names, battles, migrations, food issues, weather; none of this information is known first-hand. Not until the onset of European migration westward from the east coast and southwest from New France (Canada) did any historical records begin appearing to gain insight into the first 12,000 years of human history in Illinois.
Compiled by Neil Gale, Ph.D.