2002 Draft Natural Resources Management

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As the name suggests, the Superior Lobe originated near the area that is now known as Lake �uperior. 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,OOQ 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, Iake and stream sediments, and unsorted material, called till. This complex pattern of Grantsburg Sublobe glacial material res�ltcd in different landforms among the parks that is briefly summarized below. Acorn Park — occurs on typically loatn-textured till ranging from loamy sand to clay. Central Park — occurs on a sandy lake sedimez►t complex (Anoka Sandplain}, as well as loam- textured till. Also present in Central Park are peat deposits, which formed in wetlands since the glaciers rctreated. Langton Lake Park — includes a small amount of lake sediment (Anoka Sandplain}. Langton Lake itsclf largely occurs on till beneath as much as 20 feet of sandy lake sediment. Reservoir Woods — This is the only studied park that has glacial deposits at the surface frorn twa different glacial advances. The m,ajority of the park is cornprised of Grantsburg Sublobe deposits, including till beneath stream sedirnent, rneltwater sediment, as tiveil as a very smail area of sandy lake sediment (Anoka Sandplain} on the northwest corner of the park. The hilltop near thc reservoir entrance extending to the southwest side of the park, as well as thc area just southeast of Dale Street is comprisecf of coarse meltwater stream sediments Superior Lobe. This material was depasited earlier than the Grantsburg Sublobe material. In addition, a glacial valley extends fram thc northwest to the southeast in the park that is interprcted as a partly collapsed, partly buried, or stibglacial drainageway. Villa Park — is situatecf alora� a northwest-southeast trending glacial valley that is interpreted to be a partly collapsed, partly buried, or subglacial draina�eway. Tl�e majority of the siarface deposits in this partc are composed of Grantsburg Sublobe till. Ciry of Rose�•ille 7 Parks Natural Resource Mnnagenlenl