Ancient Lake Warren EarthCache

It is emphasized that there is absolutely no collecting of any kind.
No picking flowers or collecting acorns and taking them home.



Welcome To The Girdham Road Sand Dunes
Oak Openings Preserve Metropark



Ancient Lake Warren

It is generally accepted that the Great Lakes did not exist in preglacial times, but are the cumulative result of several phases of glaciation that took place during the last 1.5 million years (the Quaternary Period). It is also believed that some sort of system of large lakes existed in conjunction with the earlier glacial and interglacial episodes, but the character and configuration of the present Great Lakes are the products of the final deglaciation of their drainage basin that began around 14,800 years before the present (14,800 BP). At that time several major lobes of the Laurentide Ice Sheet characterized the margin of the continental glacier within the Great Lakes area. As the margins of these lobes retreated, glacial meltwater and precipitation drained southward to the Gulf of Mexico because higher land or glacial ice blocked flow in other directions. Ice-marginal lakes (or proglacial lakes) form when the land in front of the ice margin slopes toward the ice, allowing meltwater to pond directly in contact with the ice.

Further retreat of the margins of the Michigan and Huron-Erie lobes resulted in the impoundment of water between the ice margin and moraines (the tops of which were at higher elevations than was the ice margin) formed previously by the glaciers. Thus, a series of lakes came into existence, one side of which lay against the ice margin; these sort of lakes are called proglacial lakes. This is the first phase of the complex development of the present Great Lakes, which are the result of such factors as erosion and deposition by the glaciers, blockage of drainage by glacial ice, subsidence of the land beneath the glacier's immense weight, followed by rebounding of land during and after glaciation, and postglacial lowering of the lake outlets by erosion. The following stages summarized some important aspects of the further development of the lakes. The first proglacial lakes to form were Maumee and Chicago, associated with the Huron-Erie and Michigan lobes, respectively.

The resultant lake in the Erie basin was named Glacial Lake Whittlesey, which had a lower level than its predecessor, the Maumee. The retreating Huron-Erie lobes, coupled with outlet changes, caused lake level fluctuations to deposit and rework coastal surfaces. Current Lake Erie water levels are significantly lower that its ancestral Lake Warren counterpart, exposing previous shoreface surfaces.

These same forces over centuries lead further to creation of subsequently smaller and lower-elevated Glacial Lake Warren. After Lake Warren I, II, and Wayne decreased in size and elevation, an ice advancement enlarged the body of Wayne, leading to the creation of Lake Warren III (elevation 206 m) and it's highlighted shoreline on the above image.

The Oak Openings sand belt of northwestern Ohio and southeastern Michigan formed during this recession of the Huron–Erie Lobes, when northwest Ohio was inundated by this series of ancestral lakes of the Lake Erie basin. To the north it extends almost to the Ohio-Michigan line. It is a band of sandy soil that is approximately 22 miles long and varies from 3 to 5 miles wide. This sand beaches consist of uniformly fine to medium grained sand up to 35 feet deep and in an irregular ridge 1 to 2 miles broad deposited on lacustrine clay.

But what was the Oak Openings area, and why are there sand dunes?

To receive credit for this earthcache:

1. Go to posted coordinates. Take an elevation reading This will be your Base #1 reading. Record the timeframe when these sand dunes were created, what these dunes are constantly doing, and a few rare species that can be found here.
2. (N 41° 33.346 W 083° 51.222) Go to main sand dune entrance. Take another elevation reading. This will be your Base #2 reading.
3. (N 41° 33.323 W 083° 51.106) & (N 41° 33.293 W 083° 51.094 ) Go to third and fourth set of coordinates. These are also convenient locations of benches. Take elevation readings at both of these spots. This is your ridge reading.
4. Convert the given elevation of Lake Warren III to feet. Using what you now know of the history of the area, along with your readings and calculations, see if you can determine what the Oak Openings area was during the time Lake Warren III existed.
5. Send your answers in a geocaching.com email to us.
6. (optional) Pics of you, or something else, in this beautiful and fascinating area.

This cache is placed with the permission of the Metroparks of the Toledo Area.
For more information on this metropark, or any others, please go to:
http://www.metroparkstoledo.com/metro/parksandplaces/index.asp?page_id=510



About the Lark Sparrow



The Lark Sparrow, listed by the Ohio Division of Wildlife as an endangered species, nests in grassland habitats with scattered shrub layers, disturbed open areas, as well as patches of bare soil. In the Oak Openings area west of Toledo, lark sparrows occupy open grass and shrubby fields along sandy beach ridges. These summer residents normally migrate out of Ohio shortly after their young fledge or leave the nest. Lark sparrows begin nesting during May. They build an open-cup nest that is low to the ground. The eggs hatch in 11-12 days. Most lark sparrows fledge during June.