The Ants of Ramsey County, North Dakota

Abstract

Ramsey County lies in the east-central part of North Dakota. Physiographically, the county is in the Western Young Drift section of the Central Lowland province (Fenneman, 1938). The area is entirely covered by a mantle of glacial drift, deposited largely by the last Wisconsin glacier. Apparently the bedrock surface, which is the Pierre shale of Cretaceous age, is nowhere exposed. Most of the drift is derived from the underlying Pierre shale. A variety of glacial features is present in Ramsey County. Several end moraines cross the area with a northwest-southeast trend. Because of the impermeability of the till, the depressions of the moraines are frequently occupied by marshes and lakes. Boulders are commonly found on the surface of undisturbed till but may be seen in piles on farms where they have been removed for cultivation of the land. These boulders form excellent nesting sites for certaini species of ants. Much of the county is covered by thin ground moraines, and these parts are gently rolling areas with a local relief of no more than 20 to 30 feet. An outwash plain of sands and gravels begins in