Historic truths tend to dim more quickly than we imagine, whether family history, neighborhood history, national and world history, or geologic history. Perhaps modern distractions obscure healthy interest in the past. We have discovered that important knowledge about the recent Wisconsin Ice Age is weak for many modern residents, even residents living in wonderful glacial areas. Facts about the Wisconsin glacier are incredible, both how recently they occurred and their astonishing scope of events. It swathed much of the Earth’s surface in thick ice, especially in the Northern Hemisphere, and most especially, in North America. The ice pack bathed the land in thick ice from 120,000 BC to about 13,000 BC, with the maximum coverage at 20,000 BC. In terms of the broad span of Earth history, these time frames are but a geologic moment ago.
My childhood occurred in the area of upstate New York in the Syracuse region. We enjoyed family and church outings to the Finger Lakes—Seneca and Cayuga—as well as several recreational invitations from generous church families who owned camps on Otisco Lake, the small, easternmost Finger Lake. Fair Haven State Park on Lake Ontario was a popular recreation venue. We mention these events to introduce readers to incredible realities of glacial geology in that region. Those stunning locales, including Lake Ontario and all of the unique Great Lakes, were leftovers of the Wisconsin glacier. In the recesses of my childhood recall are memories of Clark’s Reservation, a small 377-acre state park south of Syracuse. An internet link pronounces the park a geologic wonder and a botanist’s paradise.
When the mile-thick Wisconsin ice sheet melted over the span of several thousand years, a tremendous quantity of meltwater yielded to the power of gravity. Sea level, which had fallen nearly 400´ eventually returned to its pre-ice age level. Tremendous quantities of meltwater found their way to the sea. Huge lakes formed at the south margins of the glacier. As the lakes filled with more and more meltwater they needed an escape route to the ocean. Sometimes the glacier deposited moraines of soil and rock marking its farthest advance. The moraines formed retaining dams which frequently gave way, diverting the water into new drainage patterns. The Syracuse channels carried meltwater to lower elevations, eventually to the Mohawk River Valley and the Atlantic Ocean. The tough limestone cap rock eroded differently from the weaker bottom rock layers in the channel. One channel formed falls several feet higher than Niagara Falls. The falls overlooked an impressive canyon. The “plunge pool”at the bottom of the falls formed Glacier Lake, still present at Clark’s Reservation State Park—6.2 acres in area and 52 feet in depth. It is a rare meromictic lake in which layers of water at different temperatures do not mix year round. Of course, no water flows over the falls any longer. It is a “fossil” waterfall.
When water rushed off Earth’s surface from the melting Wisconsin glacier toward lower elevations, writers have often described the enormous outflow as a torrent, a colorful term reserved for the most powerful and impressive floods. Many historic torrents have resulted from the meltback of continental glaciers. Ocean levels rose nearly 400´ after the glacier retreated to its present dimensions. We are in the last stages of the Wisconsin event. Slight sea level rise still occurs but current Earth temperatures have assumed remarkable stability in the last several thousand years. Extreme concern over further ocean rise and slight warming of planetary temperatures from anthropocentric CO2 is unwarranted, notwithstanding intense political alarmism. Our current climate stability is a blessing to humanity and has made possible the exponential expansion of civilization and human population.
In past posts we have referred to northern New Jersey’s Great Swamp. The swamp is a glacial remnant of Lake Passaic, a 300 square mile lake which existed 14,000 to 19,000 years ago and may have been as much as 300´ deep at times. The swamp is now only about 12 sq. mi. in area but is designated a National Wildlife Refuge. In researching a detailed report by a New Jersey Geological Society bulletin from 2007, we found the term “torrent” used in connection with an event occurring when the melting ice exposed notches in far northern New Jersey. (In 1960 one colleague actively campaigned to prevent the Port Authority of New York from constructing a new jetport in the Great Swamp. Four 10,000´ runways would have devastated a natural habitat. The campaign resulted in eventual victory in 1964.) The location was at the extreme southern end of the former Wisconsin ice sheet. Over several thousand years, the lake levels fluctuated and drainage patterns were altered, including the diversion of the Passaic River from a southerly to a northeast course.
We contemplate a future visit to Kankakee State Park and Starved Rock State Park just southwest of Chicago IL. The term “torrent” is frequently used to describe an event of even greater impact than the two events described above. The long-lasting flood first occurred about 19,000 years ago. It resulted from meltwater of the Wisconsin ice sheet breaching the Valparaiso Moraine in northwest Indiana and northeast Illinois. The torrent was usually confined to river valleys but sometimes overflowed banks of the rivers, becoming a flow up to 20 km wide. Curiously, the Valparaiso Moraine presently marks the divide between generally north-flowing drainage which flows east to the St. Lawrence River and the Atlantic Ocean while water flowing away from the moraine winds up flowing south toward the Mississippi and the Gulf of Mexico.
Glacial meltwater flow was always complex and changing. It occurred over many years. Some of the most spectacular glacial topography arose where the torrent carved deep channels and left tributaries “hanging” above the valleys in somewhat higher elevations, forming waterfalls. Such features seem unlike much of the topography in Illinois, which is currently known by its nickname—the Prairie State.
In a future post we will examine how our God oversees the flow of geological Earth events for the benefit of created humanity. This includes the cyclical advance and retreat of ice ages. We trust that the above post helps readers establish that “God is in control,” whether in the advance and retreat of planetary glaciation, or in the everyday life-sustaining miracles of our bodily processes! Are significant glacial events miraculous? To help you answer, we encourage readers to upload this link:
