Two Creeks Buried Forest State Natural Area is a site in the

Wisconsin State Natural Areas Program The Wisconsin State Natural Areas Program is a conservation program created to highlight and protect areas with outstanding natural resource, natural or archaeological site, archaeological resources in the U.S. state of Wisconsin. There are current ...

and a unit of the

Ice Age National Scientific Reserve The Ice Age National Scientific Reserve is an affiliated area of the National Park System of the United States comprising nine sites in Wisconsin that preserve geological evidence of glaciation. To protect the scientific and scenic valu ...

. The site lies in the northeast corner of Manitowoc County on the shore of

Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that o ...

north of

Two Creeks, Wisconsin Two Creeks is a town in Manitowoc County, Wisconsin, United States. The population was 551 at the 2000 census. The unincorporated community of Two Creeks is located in the town. Geography According to the United States Census Bureau, the town has ...

, USA. Periodically exposed in a steep lakeshore bluff is a

stratum In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

, known as the Two Creeks forest bed. It contains stumps, logs, branches, pine needles, pinecones, moss, and other

forest litter The forest floor, also called detritus, duff and the O horizon, is one of the most distinctive features of a forest ecosystem. It mainly consists of shed vegetative parts, such as leaves, branches, bark, and stems, existing in various stage ...

and is sandwiched between layers of

glacial till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...

. This is an important site in Great Lakes geochronology because it firmly establishes the timeframe of advances and retreats during the last glacial period in this region.Black, R.F., 1974
''Geology of the Ice Age National Scientific Reserve of Wisconsin''.
''U.S. National Park Service Scientific Monograph Series,'' 2, 234 pp. As summarized in Rech and others, various studies have dated the buried logs and stumps from the Two Creeks forest using

radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was de ...

and analyzed their growth rings to determine a minimum lifespan for the forest.Rech, J.A., Nekola, J.C. and Pigati, J.S., 2012. ''Radiocarbon ages of terrestrial gastropods extend duration of ice-free conditions at the Two Creeks forest bed, Wisconsin, USA.'' ''Quaternary Research'', 77(2), pp.289-292. Initial research into the age of this buried forest indicated an calibrated age range of ~13,840–13,620 cal BP and a minimum lifespan for the forest of ~230 to 250 yr.Broecker, W.S. and Farrand, W.R., 1963. ''Radiocarbon age of the Two Creeks forest bed, Wisconsin.'' ''Geological Society of America Bulletin'', 74(6), pp.795-802.Kaiser, K.F., 1994. ''Two Creeks Interstade dated through dendrochronology and AMS.'' Quaternary Research'', 42(3), pp.288-298. Later research by Leavitt and others indicated a minimum lifespan of 329 yr for the Two Creeks and an age range of 13,760–13,530 cal BP. Leavitt, S.W., Panyushkina, I.P., Lange, T., Cheng, L., Schneider, A.F. and Hughes, J., 2007. ''Radiocarbon “wiggles” in great lakes wood at about 10,000 to 12,000 BP.'' ''Radiocarbon'', 49(2), pp.855-864. The lower layer of glacial till was deposited during the end of the Woodfordian substage of the Wisconsin glaciation. The remains in the park demonstrate that a warmer interval, called the ''Twocreekan substage'', followed in which the

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such a ...

retreated and a forest of

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfam ...

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...

, and hemlock grew. Then the climate cooled again and the Greatlakean substage began.Evenson, E.B., Farrand, W.R., Eschman, D.F., Mickelson, D.M. and Maher, L.J., 1976. ''Greatlakean substage: a replacement for valderan substage in the lake Michigan basin.'' ''Quaternary Research'', 6(3), pp.411-424. A glacial tongue blocked Lake Michigan's drainage, causing the water level to rise and flood the forest, carrying in sediments which buried the forest floor. The glacier proceeded to flow over the forest, flattening it and ultimately depositing another layer of glacial till over it.Mickelson, D.M., Hooyer, T.S., Socha, B.J., Winguth, C., 2007. ''Late-glacial ice advances and vegetation changes in east-central Wisconsin.'' In: Hooyer, T.S. (Ed.), ''Late-Glacial History of East-Central Wisconsin'', ''Wisconsin Geological and Natural History Survey Open-File Report'', 2007-01. pp. 72–87. Two Creeks Buried Forest State Natural Area is open to visitation. There is an historical marker at the location. The site has no trails or displays, but visitors can park in the northwest corner of the site and wander freely across the grounds. Collection of any material is prohibited.Meyer, T., ed. ''Wisconsin, Naturally: A Guide to 150 Great State Natural Areas''. Madison, Wisconsin, Wisconsin Department of Natural Resources, Bureau of Endangered Resources, State Natural Areas Program, 184 pp.

References

External links

Two Creeks Buried Forest State Natural Area
from the National Park Service {{authority control Ice Age National Scientific Reserve Cenozoic paleontological sites of North America Protected areas established in 1967 Protected areas of Manitowoc County, Wisconsin State Natural Areas of Wisconsin Paleontology in Wisconsin Fossil parks in the United States 1967 establishments in Wisconsin