|
|
Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
|
OP
Carpal Tunnel
Joined: Jan 2001
Posts: 13,858 |
Years ago reading Yearbook of Agriculture, there was often
mention of soil type called "loess" but no background of term.
?
As glaciers advanced and retreated during the Pleistocene epoch, four ice ages ocurred. The Nebraskan, which was the first ice age, followed by the Kansan, the Illinoian, and the Wisconsin. During these ice ages, a very fine rock powder was produced by way of scouring the exposed rock as glaciation took place, that powder is known as rock flour or silt (http://www.isgs.uiuc.edu/tours/outliers/geogram5.htm). As the silt accumulated, it could be transported by the wind as the glacier retreated or by glacial outwash as the silt dried during which the climate changed from winter to spring.
As the warmer climate approached, the glacier would begin to melt, saturating the rock flour, which allowed it to be transported as sediment load in streams or rivers. As velocity of the stream decreased, either by the onset of winter or loss of slope angle, the sediment load would drop out and accumulate along the banks which produced a mud of very fine silt.
With the drying of the mud, the wind could now pick up the silt particles and transport them according to their size(http://www.isgs.uiuc.edu/tours/outliers/geogram5.htm). The coarser particles would drop out first, closer to the source and the fine particles would be the last to drop out, which would be farthest from the source.
In the midwest section of theUnited States, the Missouri River Flood Plain is the source of silt that winds transported eastward, into the flood plains. Accumulation of silt over many years produced landforms of various sizes and shapes. The main component of the landforms produced is called loess or as stated previously, the definition of loess is " A blanket deposit of buff-colored calcareous silt, homogeneous, nonstratified, weakly coherent, porous, and friable. A rude vertical parting allows it to stand in steep or vertical faces. Loess covers wide areas in northern Europe, eastern China , and the Mississippi Valley. It is considered to be windblown dust of Pleistocene age."( Bates and Jackson, 1984).
Three types of loess can be found throughout the midwestern states, the Loveland loess, the Pisgah loess, and the Peoria loess (http://pubs.usgs.gov/info-handout/loess/). Each loess having its own characteristics can be found intermixed with glacial till, alluvium, sand, and gravel.
|
|
|
|
|
Joined: Oct 2000
Posts: 5,400
Carpal Tunnel
|
|
Carpal Tunnel
Joined: Oct 2000
Posts: 5,400 |
the yellow river in china, gets its name from the yellow loess soil that get washed into the river as silt.
when traveling cross country a few years ago, we (son and i) detoured to norther nebraska to visit car henge. (stone henge, recreated with car frames instead of stone monoliths)
i was rather impressed with the soil of nebraska. it was not at all the same as eastern soil.. it seemed like fine grey silt. my soil in my (last dying days) yard, is sandy, (given the all of long island is a giant sand bar) and years of composting and work, have improved it, but it is still sandy, well drained soil. but it is also dark, (well the first six inches, after that, a sandy layer, and finally, 12 to 15 inch down pure sand, suitable for mining-- the sand is a nice golden color.)
previously, i had a (house)yard with clayish soil. (again, years of work and composting had improved the texture, but it was pretty stiff clay, after you went down a bit.
by contrast, the soil in nebraska was almost white! i don't think i have ever seen loess. (but i have seen the red clay that is so predominant in the southern parts of US.)
We have a poster from the loveland area in ohio.. maybe he can tell us about the soil there abouts...
and do we have anyone here from peroria? or pisgah(where is that?!)
|
|
|
|
|
Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
|
|
OP
Carpal Tunnel
Joined: Jan 2001
Posts: 13,858 |
Where is Pisgah? A good question. I found sites including
much of Appalachian area, but also from as far away as
California.
The original according to dictionary, is in Israel:
Pisgah
Heb pisga, lit., peak, summit6 Bible mountain ridge east of the N end of the Dead Sea: Deut. 3:27 See NEBO, Mount
|
|
|
|
|
Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
|
|
OP
Carpal Tunnel
Joined: Jan 2001
Posts: 13,858 |
A second term I encountered in The Yearbook of Agriculture was "podzol", on of several words of Russian origin. Here is URL with picture: http://edu.suomussalmi.fi/lukio/globe/podsoli.htm
|
|
|
|
Forums16
Topics13,913
Posts229,317
Members9,182
| |
Most Online3,341
Dec 9th, 2011
|
|
|
0 members (),
706
guests, and
1
robot. |
|
Key:
Admin,
Global Mod,
Mod
|
|
|
|
