4-1 Photo by Shawn Winsor Frog in Pond Section 4. Environmental
Photo by Shawn Winsor Frog in Pond Section 4. Environmental Inventory & Analysis 4. A. Geology, Soils, and Topography Lancaster is located along the eastern margin of the Central Upgrade region of Massachusetts, a region of moderate relief characterized by numerous, irregularly shaped granite hills, plains, and glacial features known as monadnocks. Throughout the region, forests are interspersed with wetlands, ponds, lakes, rivers, and streams. Where the North Nashua and South Nashua Rivers join in Lancaster at “The Meeting of the Waters”, the main stem of the Nashua flows northward at an elevation of 220’ above mean sea level. To the north and west, rolling hills reach elevations of more than 550 feet. This area is highly conducive to rapid runoff. The Wisconsin Glacier of the Pleistocene epoch, which ended approximately 12,000 years ago, was the last major advance in North America of the Laurentide ice sheet which radically changed the landscape. Two miles thick in places, it caused drumlins to be formed by riding over loose bedrock and, as it melted and by dumping boulders, stones and soils along its southerly receding face. Called glacial till, this heterogeneous material covers much of the landscape in Worcester County. Glacial outwash was formed by melt water from the receding glacier picking up glacial till, sorting it by size and water velocity, and redepositing it downstream. The region surrounding the Nashua River Valley is an example of this outwash plain. Alluvium, made up of sand, silt, or clay, was deposited upon the land by streams. Areas of glacial till generally range from gently sloping to strongly sloping.
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