2002 Natural Resources Management

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As the name suggests, the Superior Lobe originated near the area that is now known as Lake Superior. This ice advance occurred about 20,000 years ago. Grantsburg Sublobe deposits made later largely cover the sediments left by this event. During the most recent ice advance, a major ice sheet moved from the northwest, through western and central Minnesota into central Iowa. While this occurred, the Grantsburg sublobe moved to the northeast through the Twin Cities approximately 16,000 to 12,000 years ago. As ice sheets to the west and northwest began to stagnate and retreat, they left behind a variety of deposits including outwash, lake and stream sediments, and unsorted material, called till. This complex pattern of Grantsburg Sublobe glacial material resulted in different landforms among the parks that are briefly summarized below. Acorn Park — occurs on typically loam- textured till ranging from loamy sand to clay. Central Park — occurs on a sandy lake sediment complex (Anoka Sandplain), as well as loam- textured till. Also present in Central Park are peat deposits, which formed in wetlands since the glaciers retreated. Langton Lake Park — includes a small amount of lake sediment (Anoka Sandplain). Langton Lake itself largely occurs on till underlying as much as 20 feet of sandy lake sediment. Reservoir Woods — This is the only studied park that has glacial deposits at the surface from two different glacial advances. The majority of the park is comprised of Grantsburg Sublobe deposits, including till beneath stream sediment, meltwater sediment, as well as a very small area of sandy lake sediment (Anoka Sandplain) on the northwest corner of the park. The hilltop near the reservoir entrance extending to the southwest side of the park, as well as the area just southeast of Dale Street is comprised of coarse Superior Lobe meltwater stream sediments. This material was deposited earlier than the Grantsburg Sublobe material. In addition, a glacial valley extends from the northwest to the southeast in the park that is interpreted as a partly collapsed, partly buried, or subglacial drainageway. Villa Park — is situated along a northwest- southeast trending glacial valley that is interpreted to be a partly collapsed, partly buried, or subglacial drainageway. The majority of the surface deposits in this park are composed of Grantsburg Sublobe till. City of Roseville 9 Parks Natural Resource Management