Pymutuning Lake EarthCache
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Pymatuning lake was created in 1934 when the construction of the dam was completed, but this was not the first time a lake was here. Geologist believe that a lake about the size of the current Pymatuning lake was here prior to the last ice age. During the ice age a glacier moved across the mountains flatting them down and filling in the lake. This gives pymatuning lake a very unique feature. Even though the lake has a max length of 17 miles and a max width of 1.6 miles the lake is only 35 feet deep at the deepest point.
Glaciers are categorized by their morphology, thermal characteristics, and behavior. Alpine glaciers, also known as mountain glaciers orcirque glaciers, form on the crests and slopes of mountains. An alpine glacier that fills a valley is sometimes called a valley glacier. Larger glaciers that cover an entire mountain, mountain range, or volcano are called ice caps or ice fields.[4] Ice caps have an area less than 20,000 mile² by definition.
Glacial bodies larger than 20,000 miles² are called ice sheets or continental glaciers. Several miles deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of fresh water, enough that if both melted, global sea levels would rise by over 70 meters. Portions of an ice sheet or cap that extend into water are called ice shelves; they tend to be thin with limited slopes and reduced velocities. Narrow, fast moving sections of an ice sheet are called ice streams. In Antarctica, many ice streams drain into largeice shelves. However, some drain directly into the sea, often with an ice tongue, like Mertz Glacier.
Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin and Ellesmere Islands in Canada, Southeast Alaska and theNorthern and Southern Patagonian Ice Fields. As the ice reaches the sea, pieces break off, or calve, forming icebergs. Most tidewater glaciers calve above sea level, which often results in a tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by the climate change than those of other glaciers.
Thermally, a temperate glacier is at melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below freezing point from the surface to its base, although the surface snowpack may experience seasonal melting. A sub-polar glacier includes both temperate and polar ice, depending on depth beneath the surface and position along the length of the glacier.
Glaciers erode terrain through two principal processes: abrasion and plucking.
As glaciers flow over bedrock, they soften and lift blocks of rock into the ice. This process, called plucking, is caused by subglacial water that penetrates fractures in the bedrock and subsequently freezes and expands. This expansion causes the ice to act as a lever that loosens the rock by lifting it. Thus, sediments of all sizes become part of the glacier's load. If a retreating glacier gains enough debris, it may become a rock glacier, like the Timpanogos Glacier in Utah.
Abrasion occurs when the ice and its load of rock fragments slide over bedrock and function as sandpaper, smoothing and polishing the bedrock below. The pulverized rock this process produces is called rock flour and is made up of rock grains between 0.002 and 0.00625 mm in size. Abrasion leads to steeper valley walls and mountain slopes in alpine settings, which can cause avalanches and rock slides. These add even more material to the glacier.
Glacial abrasion is commonly characterized by glacial striations. Glaciers produce these when they contain large boulders that carve long scratches in the bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks, lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock.
Glacial deposits are of two distinct types:
• Glacial till: material directly deposited from glacial ice. Till includes a mixture of undifferentiated material ranging from clay size to boulders, the usual composition of a moraine.
• Fluvial and outwash sediments: sediments deposited by water. These deposits are stratified by size.
Larger pieces of rock that are encrusted in till or deposited on the surface are called "glacial erratics". They range in size from pebbles to boulders, but as they are often moved great distances, they may be drastically different from the material upon which they are found. Patterns of glacial erratics hint at past glacial motions.
The first thought of construction for a dam was in 1911, when a massive flood in 1913 caused $3 million in damage and took several lives. The Pennsylvania General Assembly approved a budget of $1.2 million to build at dam across the Shenango, but Governor John K. Tener slashed the budget to just $100,000. The Pennsylvania legislature took action again in 1917, this time approving a $400,000 budget under the condition that the needed land in Ohio be purchased by the private sector. The Pymatuning Land Company was formed and raised the funds to purchase the needed Ohio properties. The land was finally acquired in full by 1931 when Governor Gifford Pinchot approved $1.5 million to complete the dam. 7,000 men began work on the dam in 1931. The final total cost of the dam was $3,717,739. The lake now holds 64.3 billion US gallons of water, covering 17,088 acres and 70 miles of shoreline. The lake has served to provide a water supply for the Shenango and Beaver valleys, it has lessened the damage caused by floods, and provided recreation for the people of Ohio and Pennsylvania. Two state parks, each named "Pymatuning State Park", are on the lake in Ohio and Pennsylvania.
A scenic 2-mile-long causeway bridge spans the middle of the lake, connecting the towns of Espyville on the Pennsylvania side of the lake and Andover on the Ohio side. The bridge is crowned in the middle, with tall pillars and broad ducts underneath to allow lakewater to flow freely across the reservoir, and to permit the passage of sailboats and other pleasure craft travelling from one half of the lake to the other. The bridge is also equipped with small concrete and earthen pull-offs large enough for several vehicles apiece, with concrete staircases and walkways below the parking spaces to allow travelers to stroll down and fish or sightsee beside the bridge.
To log this cache you must complete the following:
1. Answer the following questions DO NOT POST THE ANSWERS WITH YOUR LOG OR IT WILL BE DELETED:
A. What type of glacier do you think was at this location and why?
B. What type of glacial deposits do you think filled in the lake?
C. What crop was grown here before the lake was formed and why do you think they grew so big?
D. How wide is the dam at the top? The bottom?
2. (Optional) Take a picture of yourself and your GPS in front of the gate house.
NOTE: Any found logs without us receiving an email with the answers will be deleted. Our email is acagcachers@gmail.com. If you have any questions feel free to email us and we will be glad to answer them for you.
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