Missouri's Icy Past

Nothing, not even diesel-powered, Detroit iron, moves earth as effectively as glacial ice.

Like giant bulldozers, ancient glaciers plowed across northern Missouri, dramatically altering the landscape as part of a relentless, natural renovation project that occurred nearly 500,000 years ago. These thick rivers of ice left behind a blanket of mixed rock, sand and clay as they pushed innumerable tons of earth southward into the glacial melting zone.

Glacial Effects in Northern Missouri

The sheer amount of land covered by glaciers became apparent to me when a geologist showed me a fist-sized, dull brown mineral sample he found in a stream bed south of St. Joseph. It was taconite, a type of iron ore, from the Mesabi Range in northeastern Minnesota.

The sheer amount of land covered by glaciers became apparent to me when a geologist showed me a fist-sized, dull brown mineral sample he found in a stream bed south of St. Joseph. It was taconite, a type of iron ore, from the Mesabi Range in northeastern Minnesota.

It arrived here during one of two early glacial advances, known as the Nebraskan and the Kansan, when vast ice sheets worked like gigantic conveyor belts to carry a variety of rocks and minerals south from the northern U.S. and southern Canada. When the climate warmed, the ice melted and deposited minerals like taconite as far south as St. Joseph. The mineral in my hand had traveled nearly 500 miles!

Large boulders in northern Missouri provide an even more impressive testament to the power of glaciers. Called "erratics" by geologists, they are so novel that many are noted in Thomas Beveridge's book, "Geologic Wonders and Curiosities of Missouri." An erratic northwest of Milan in Sullivan County is about as tall as a basketball goal and measures 20 feet wide by 24 feet long. Its estimated weight is about 384 tons.

Even that pales in comparison to some of Missouri's other glacial artifacts. For example, main channels of ancient rivers and streams in Missouri's northwest corner once drained primarily from west to east, rather than north to south, as our streams do today. Their valleys were buried under till, a mixture of clays, sands and gravels left by melting glaciers. Only after the Kansan and Nebraskan ice sheets disappeared did the Missouri River attain its present course in this region.

Today, wells are drilled into these buried ancient river channels. In northern Missouri, the water quality from these sites is better