The Quaternary
Geologic Age |
What Happened |
Carbon 14 Dates |
|
Holocene |
Development of modern soils and stream deposits and erosion. |
Today |
|
Wisconsinan Glaciation |
Wind-blown loess covers most of Iowa outside of the Des Moines Lobe. |
12,500
31,000 |
|
|
The Des Moines Lobe reaches north-central Iowa and deposits its debris. |
14,500
17,000 |
|
|
Early Wisconsinan glaciation is evident in northwestern Iowa under a blanket
of loess. |
26,000
40,000 |
|
Sangamonian Interglacial Stage |
Development of a soil layer and erosion on older deposits. Evident across most
of Iowa, covered by Wisconsinan tills and loess. |
55,000 |
|
Illinoian Glaciation |
Glacial tills deposited along the southeastern edge of Iowa. |
130,000 |
|
Yarmouthian Interglacial Stage |
Development of a soil layer and erosion on older deposits. Evident across most
of Iowa, covered by Illinoian tills and Wisconsinan tills and loess. |
300,000 |
|
Pre-Illinoian Glaciation |
As many as 20 glacial advances may have crossed Iowa. Their evidence lies buried
under more recent sediments and soil development. Evident across most of Iowa,
covered by Illinoian and Wisconsinan tills and loess. |
500,000
2,500,000 |
«« back ::: |
