Ed: The largest areas of buried forests under sand dunes in the Midwest are probably in the Sleeping Bear Dunes National Lakeshore, and elsewhere along the east shore of Lake Michigan. I say this because of the massive size of the dunes there. Its hard to judge what the largest dunes in the U.S. are. Factors such as whether to count only actively moving dunes or also those covered by vegetation come into play. The claim has been made that SBD dunes are the largest, and the same claim has been made for other dune systems. Clearly Great Sand Dunes are the tallest, but are only about 3 x 6 miles, which is small compared to the dune complex on the east shore of Lake Michigan, especially if one counts dunes outside of SBD, including the state parks, Indiana Dunes and other dunes along the lake. Kobuk Dunes in Alaska might be the biggest too, there are 200,000 acres of dunes, but only 20,000 acres are actively moving and have buried boreal black and white spruce forests. In any case, the Lake Michigan dunes are actively moving all the time, and buried forests from a few hundred to a few thousand years old occur.
SBD and other areas along Lake Michigan also have the buried spruce forests from about 11,000 ybp, which were knocked down and buried in glacial drift by a southward readvance of the glaciers (Ed, I can't remember the name of the readvance right now, but you probably do). This glacial drift is either under the sand dunes or in some cases is exposed along the shore of the lake in areas without dunes. These buried forests occur all around northern Lake Michigan, and 11,000 year old driftwood is apparently common on the beach. This wood is so well preserved that carbon-14 dating is usually necessary to differentiate it from modern driftwood. Apparently the entire area from Green Bay to Manitowoc, WI, from Lake Michigan to Lake Winnebago is underlain by the Two Creeks Buried Forest--about 1,000 square miles, where it is reported that a layer of wood is encountered when new wells are drilled. Two Creeks Buried Forest Natural Area near Manitowoc, WI has the exposed 11,000 year old layer, with wood, pine cones, forest floor mosses and other organisms that were living in the forest. Lee Edward Frank wrote: > Barry, > > I don't know much about Indiana Dunes. It is my understanding that it > is essentially a prairie type ecosystem there without trees. There > may be buried forest there. I don't know. > > The Desert of Maine is a glacial outwash deposit. It does have some > trees at least partially buried around its edges. It has been a long > time since I visited it. hey are planting trees in some areas around > the edge of the Sahara Desert trying to stabilize the dunes. > Overgrazing in the dry climate has made the desert move and enlarge > over the last couple thousand years. Wikipedia reports: "It has been > reported that the Sahara is expanding south by as much as 30 miles (48 > km) per year, overwhelming degraded grasslands, taking over the Sahel, > the dry tropical savanna that has defined the Sahara's southern limit. > Global warming and poor farming methods have been given as possible > causes The spreading of deserts is known as "desertification," and the > phenomenon is occurring in other desert areas worldwide." The dune > fields along the coasts of the oceans and big lakes are generally very > dynamic. Where they are stable for awhile forests will grow, then at > some point the dunes will move again and bury the trees. > > A NPS document on Pictured Rocks NL comments: "That habitats and > disturbance regimes on the Grand Sable Dunes plateau have changed > drastically in the past is witnessed by the presence of “ghost > forests” of apparent various age within the dune field and charcoal > fragments associated with several ancient soils. Studies of fire > history, rare plant distribution, soils, forest ecology and > geomorphology of the dune field and northern hardwood and conifer > forests surrounding it suggest that many drivers of landscape dynamism > interact in the dunes. This complex interaction produces distinctive > patterns of community types, species richness, and patch turnover > within a relatively small area." > > Edward Frank > > "The most beautiful thing we can experience is the mysterious. > It is the source of all true art and all science." - Albert Einstein > > > --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
