Loess is a sediment formed by the accumulation of wind-blown silt, typically twenty percent or less clay and the balance equal parts sand and silt that are loosely cemented by calcium carbonate. It is usually homogeneous and highly porous and is traversed by vertical capillaries that permit the sediment to fracture and form vertical bluffs. The loess in this area is believed to have been dust left after ice age glaciers ground retreated. The prevailing winds blew the dust eastward and deposited it at the base of the hills along the Mississippi River.
The word loess, with connotations of origin by wind-deposited accumulation, is of German origin and means "loose." It was first applied to Rhine River valley loess about 1821.
The loess along the Mississippi River near Natchez, Mississippi consists of three layers. The Peoria Loess, Sicily Island Loess, and Crowley's Ridge Loess accumulated at different periods of time during the Pleistocene. Ancient soils, called paleosols, have developed in the top of the Sicily Island Loess and Crowley's Ridge Loess. The lowermost loess, the Crowley's Ridge Loess, accumulated during the late Illinoian Stage. The middle loess, Sicily Island Loess, accumulated during early Wisconsin Stage. The uppermost loess, the Peoria Loess, in which the modern soil has developed, accumulated during the late Wisconsin Stage. Animal remains include terrestrial gastropods and mastodons. Loess soil forms sharp hills close to the Mississippi River and Yazoo River in western Mississippi north and south of Vicksburg. These deposits are more than 100 feet thick immediately above the river valleys, to which they are sub-parallel, and thin to trace thickness within 20 miles to the east. Streams and gulley’s are incised very deeply and sharply between the linear loess ridges.
Snail species found embedded in our loess are forest leaf-litter snails, not streambed snails. There's no ambiguity over their lifestyle, because nearly all the species found in loess are still alive. This clearly suggests that the loess surrounding the snails was deposited in some way other than by water.
To complete this earthcache, please send me the answers to the following questions:
1. The height of the hill over the nearby level ground to the west is
- 50 feet
- 100 feet
- 150 feet
2. Does the soil appear to be stable or eroding?
- Stable
- Slightly eroding
- Heavily eroding
3. Do you see any animal remains in the soil.
- No remains.
- Mastodon remains
- Snail remains
- Snail and mastodon remains.
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