Laurel Hill Plantation's
Loess Deposits

Despite being so far away, the northern glaciers put on quite a show in our area -- even though most archaeologists agree that at that time Paleolithic Man hadn't yet arrived on the American continent to witness the event. The main actor in this "show" was a very great deal of water, resulting from the Ice Age coming to an end, and the northern glacier melting and beginning its retreat northward.

"Melting" is too tame a word to describe the conversion of such huge quantities of ice into charging, exploding, sea-like rivers of frigid, frothy meltwater crashing its way to the sea. This theater of rambunctious water was the Mississippi River of its time and it passed right by the upland now occupied by Laurel Hill.

When such outrageous quantities of water rampage across the landscape, it doesn't carve out graceful meanders, or even scour for itself a comfortably deep channel, like a regular river. It forms a broad floodway composed of an interconnecting maze of channels. Some of its channels are stream-like, but others are river-like. None are very deep. Between the channels lie islands composed of sand and gravel dumped there by fast-moving currents. Some of the islands are tiny but some are large, and sometimes they are occupied by mud flats. Such networks of interconnecting channels are referred to technically as braided streams.

Braided streams can be seen today below melting glaciers in the Far North and among the higher mountains, as well as upon alluvial fans at the base of mountains issuing large amounts of meltwater when winter's snows melt during the spring. Today if you fly over the San Gabriel Mountains north of Cucamonga, California, during the spring, you can see nice ones.

According to H.N. Fisk, one of the Grand Old Men of Lower Mississippi Valley geology, the Mississippi River remained braided until about 5,000 years ago, when at last North America's continental glacier was completely melted, and the continent's weather and the sea level had returned more or less to "normal."

But, what does all this have to do with loess?

The answer lies with the fact that where braided streams with mudflats still exist today, people have been witness to some remarkable dust storms...

For example, during the 1930s a geologist by the name of Ralph Tuck studied glaciers in the Matanuska Valley of Alaska, just northeast of Anchorage. Glaciers stood twenty to forty-five miles up the valley from Tuck's observation point, and they issued floods of meltwater into braided streams. In other words, conditions there were similar to those probably existing 20,000 years ago in the lower Mississippi Valley.

The meltwater in Ralph Tuck's streams was milky-white with suspended particles of silt produced when the glaciers upstream pulverized the rocks they moved over. When the milky meltwater pooled on sand and gravel bars during periods of low outflow, mud flats occurred. Sometimes the mud dried, and when the wind stirred, dust was stirred up. Lots of dust...

Tuck described a pall of dust that during dry weather and even in the winter obscured the skies over the town of Palmer at the mouth of his valley, and surrounding territory. Surveyor's stakes driven into the ground in 1913 were found smothered by several inches of dust in 1935.

"Several inches" of dust accumulated in twenty-two years may not sound like much, but it is. For example, if for 5,000 years, five inches of dust accumulate every twenty-two years, that comes to ninety-five feet of dust! And the dust that accumulates displays the exact physical and chemical features that loess does today.

In short, no one can say with absolute certainty where loess comes from, but the best bet is that it's nothing less than wind-deposited dust from the time of the melting glacier of the last ice age.

One of the best proofs of this hypothesis is that animal fossils found at the very bottom of loess deposits date from exactly the time of the loess's first deposit, about 20,000 years ago.