Wetlands - Original Public Land Survey

At the time of the Public Land Survey between 1847 and 1907, survey crews of chainmen, axe men, and a compassman, ran the survey lines in the field and were responsible for erecting survey monuments, marking “bearing trees,” and recording all measurements in field notes.

Surveyors were also responsible for mapping the physical geography of surveyed lands including lakes, rivers, swamps, waterfalls, and areas of prairie and forest, and other features. In areas with navigable watercourses or sizeable lakes, plats sometimes include surveys of bank meanders. The surveyor’s field notes include more detailed information, such as soil type, vegetation, and mineral deposits.

Source: History of the Public Land Survey System

All features shown on the Public Land Survey were those present on the day the survey was completed and what surveyors observed along the one mile section lines being surveyed. The Public Land Survey maps of townships in Blue Earth County show small wetlands in greater numbers along the section lines where survey crews walked. Scanned maps of the Original Public Land Survey for Blue Earth County can be accessed through the Original Public Land Survey.

Other historic maps of Blue Earth County show woodlands and many shallow lakes that were drained for agricultural purposes include the Soil Survey from 1908 and a historic map from 1877.

Original Vegetation

One of Minnesota’s greatest known map makers, Francis J. Marschner, went through Public Land Survey maps and notes, word by word, to construct a map of pre-settlement vegetation for the whole state of Minnesota. The Marschner Map of Original Vegetation shows how the land looked from the perspective of surveyors on the day the land was surveyed between 1847 and 1907 for the Public Land Survey.

Source: Minnesota Historical Society

The Minnesota Department of Natural Resources used Marschner’s Map of Original Vegetation to prepare maps and reports including the Natural Vegetation at the Time of the Public Land Survey 1847-1907, Minnesota DNR, Biological Report No. 1.

Blue Earth County is located in two of the three major biomes that meet in Minnesota: the Tallgrass Prairie and the Eastern Deciduous Forest commonly called the Big Woods.

Map of Minnesota Biomes in Blue Earth County

Floodplain forests and Oak Woodlands extended along all or a portion of the major rivers in the county, including the Minnesota River, Le Sueur, Blue Earth, Maple, Cobb, and Watonwan. Significant areas of prairie wetland vegetation were noted in all corners of the county.

The vegetation types that defined these biomes were distributed on the landscape according to climate, soil and landform patterns. Natural disturbances such as fire, severe drought, windstorm, and insect outbreaks modified vegetation on a local and regional scale. Of these fire was the most important disturbance agent.

Frequent fires – started by lightning and by Indians for hunting and other purposes – helped to maintain species composition and treeless structure of the tallgrass prairie. Where fires were less frequent or intense, trees invaded the prairie in scattered groves to form woodland and parkland communities. This created a vegetation ecotone known as the forest/prairie border. Within the deciduous forest biome, where firebreaks, such a rivers, lakes and rough topography prevented the spread of fires, a dense forest of maple, basswood, and elm developed.

Source: Natural Vegetation at the Time of the Public Land Survey 1847-1907, Minnesota DNR, Biological Report No. 1.