Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION VI.3.3. Jamestown
DISCUSSION: This small sub-subsection of fine-textured moraine has a climate moderated by Lake Michigan. The presence of fine-textured soils distinguishes it from both Sub-subsection VI.3.1 to the south and Sub-subsection VI.4.2 to the east.
ELEVATION: 640 to 972 feet (195 to 296 m).
AREA: 531 square miles (1,376 sq km).
STATES: Michigan.
CLIMATE: See subsection.
BEDROCK GEOLOGY: Sub-subsection is entirely underlain by Paleozoic bedrock, primarily Mississippian shale, sandstone, and gypsum (Dorr and Eschman 1984, Milstein 1987). Glacial deposits covering the bedrock are up to 200 feet thick; bedrock is locally exposed in western Ottawa County (Akers 1938).
LANDFORMS: Most of the sub-subsection consists of broad, gently sloping ridges; but a few steep slopes occur, especially in the northeast. The highest steep ridges are approximately 200 feet high.
LAKES AND STREAMS: No large lakes. The Grand River flows through the sub-subsection. The Grand River's flood plain is broad, and the valley walls are steep.
SOILS: Most of the soils are clayey, with high water-holding capacity and low permeability (USDA Soil Conservation Service 1981). Surface soil horizons are generally loamy, and well drained and somewhat poorly drained soils are predominant (Veatch 1953).
PRESETTLEMENT VEGETATION: Fine-textured ground moraine supported a forest of almost equal parts hemlock (43 percent) and beech (41 percent), with some sugar maple, basswood, paper birch, and [red or silver] maple (Comer et al. 1993a). On the steeper end-moraine ridges, beech and sugar maple were the dominant tree species. Depressions in the ground moraine were dominated by either black ash or hemlock. Depressions in the steeper end-moraine ridges were dominated by black ash.
NATURAL DISTURBANCE: No mention of natural disturbances for this unit.
PRESENT VEGETATION AND LAND USE: Most of the lands are under agriculture, either row crops or pasture. Woodlots are generally on wet or excessively steep sites.
RARE PLANT COMMUNITIES: None identified to date.
RARE PLANTS: None identified to date.
RARE ANIMALS: Lanius ludovicians (loggerhead shrike).
NATURAL AREAS: None to date.
PUBLIC LAND MANAGERS: Grand Haven State Game Area, Riverside County Park.
CONSERVATION CONCERNS: This small sub-subsection has largely been converted to agricultural land. It is also being impacted by residential growth from nearby Grand Rapids.
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