Great Miami River Basin EarthCache
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The Great Miami River Basin (GMRB) is located in southwestern Ohio and covers 3,937 square miles. The GMRB is approximately 70 mile wide and 120 miles long. The GMRB cover 16 counties in Ohio and Indiana and the precipitation that falls on this area ultimately flows into the Great Miami River. The principal tributaries to the Great Miami River include the Stillwater River, the Mad River, and the Whitewater River. The Great Miami River drains directly into the Ohio River west of Cincinnati, Ohio.
Bedrock underlying the southern portions of the Great Miami River Basin consists of interbedded limestone and shale, the results of sediment deposition during the Ordovician age some 465 to 510 million years ago. In the northern portion of the Great Miami River Basin limestone and dolostone deposits area located on top of the Ordovician interbedded limestone and shale bedrock. The limestone and dolostone were deposited during the Silurian Age some 415 to 465 million years ago, and comprise the youngest bedrock units within the Miami Valley Region.
The current topographic and drainage conditions across the Miami Valley Region area the results of massive glaciers that covered the entire region as recently as 20,000 years ago. There were several glacial events that occurred between 20,000 and 30,000 years ago. As the glaciers advanced and retreated across the Miami Valley Region, they deposited sediments that were carried by the glaciers. The fine grained silts and clays that were deposited are referred to a till by geologist. The coarser grained material, sand, gravel, cobbles and boulders were deposited by glacial meltwater streams as they flowed on top of or beneath the glaciers. The thick sequences of sand and gravel that have be deposited in the drainage valleys are commonly referred to as the Great Miami Buried Valley Aquifer. The sand and gravel deposits within the buried valley make up a highly productive and prolific aquifer.
The Great Miami Buried Valley Aquifer abundant supply of groundwater provides drinking water to over 90% of the residents and businesses within the region. According to the Ohio Department of Natural Resources (ODNR), production well in the buried valley aquifer may yield 500 to 1,000 gallons of water per minute.
There is interaction between the buried valley aquifer and surface water. Under normal flow conditions, the buried valley aquifer discharges to the Great Miami River and many of the tributaries contributing to the total volume of stream flow. On the other hand, surface water recharges the buried valley aquifer. Well field located along the banks of the Great Miami River are able to sustain high pumping yields of groundwater due to the river providing a source of recharge to the aquifer.
The Miami Conservancy District and the United States Geologic Survey maintain a number of stream gages in along the Great Miami River. The lowest discharge ever recorded at the Hamilton was measured at 265 cubic feet per second (cfs) on July 18, 1988. The maximum stream discharge was recorded at 352,000 cfs on March 26, 1913.
To log this cache go to the posted coordinates and email me the answers to the following questions:
1. Measure the height from the base of the monument to the “Top” of the water level when the Great Miami River flowed at 352,000 cfs in 1913.
2. Decsribe what is on top on the monument.
Additionally, send me a picture of you with your GPS at the congruence of the Great Miami River and the Mad River.
Information for this cache was obtained from the Miami Conservancy District, Ohio Department of Natural Recourses and the United States Geologic Survey.
Effective 05/20/2009 all logs posted without a picture will be deleted!
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