Illinois Landcover in the Early 1800s | clearinghouse.isgs.illinois.edu

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Summary

In Illinois, the surveys began in 1804 and were largely completed by 1843. The surveyors moved across the state laying out a rectangular grid system, known as the Public Land Survey System (PLS or PLSS). They were required to keep field notebooks where they noted details about their survey (such as which kind of tree was 'blazed' or marked at the section corners), as well as notes about the quality of the landscape, mines, salt licks, watercourses, springs, mill seats and other 'remarkable and permanent things'. Once a township was finished, the surveyors were to make a map of the area. These surveys represent one of the earliest detailed maps for Illinois. They predate our county land ownership maps and atlases. These plat maps and field notebooks contain a wealth of information about what the landscape was like before the flood of settlers came into the state. Most of the over 1,700 townships in Illinois have at least one version of the original surveyor's map. Additional redrafted versions are also available for all townships. The redrafted versions were created in the 1850's at the regional GLO office in St. Louis, Missouri. Cartographers used the original maps in consultation with the field notebooks to create a more complete map of the township. It is these plat maps that the Illinois Natural History Survey used to create our Early 1800's land cover Land Cover map.

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Illinois Landcover in the Early 1800s metadata

Data

The original GLO maps and field notes are housed in the Illinois State Archives in Springfield. Microfilm copies of the maps were made in the 1960's and distributed to several state university libraries and research centers across Illinois. We borrowed the set of microfilm housed in the Illinois State Geological Survey library.

Each GLO map was scanned from the microfilm onto a laptop computer. We used Adobe Photoshop software and a Canon MS400 microfilm scanner to capture the images saving them as tiff files. The images were georectified, or spatially-referenced (using ERDAS Imagine software) against USGS Geological Survey Digital Raster Graphic (DRG) images (scanned USGS 7.5 minute topographic quadrangle maps) by matching the township and section corners on GLO images to the corresponding points on the DRG. This process allowed us to digitized or 'trace' the line work on the plat map using Geographic Information System (GIS) software (ESRI Arc/Info).

Forty two different land cover categories and features from the plat maps were digitized. All land cover categories and feature names were the ones used by the surveyors or cartographers. The names of some features seemed to varied by area of the state (probably by surveyor) and were combined. These included bluff/sand bluff, barrens/open barrens, bottoms/bottom land, field/enclosure, hills/sandy hills, high ridge/sandy ridge, island/sandy island, mound/high mound, river/wide river, ravine/gully,valley/hollow, sandy prairie/sandy ground, timber/forest/grove/wooded. Towns and roads or trails were not digitized. The attribute table item “Land_Code” has all 42 land cover categories. The attribute table item “Map” has the 12 land cover categories as displayed on the poster.

The scanned, georectified images of each township are now a permanent archive of the GLO maps. This will allow users to view the original plat maps. The separate digitized version of the plat maps is a statewide GIS coverage, which can be used on its own or as a layer in GIS analysis.

Five revisions of the data have been released. One correction was in the NW corner of present day Peoria County. The scanned township on the microfilm was mislabeled. The correct township was obtained and data was corrected. A second error was discovered in present day Adams county. A prairie area was mis-digitized and incorrectly labeled as forest. The missing lines were added and the labels were corrected. The third error set of errors included Massac and Lawrence counties. In Massac county, a pond was mis-labeled as a prairie. The label was corrected. In Lawrence county, along the Wabash river, stray lines were removed and ridge lines were added in the forest area. The forth-fifth set of errors included JoDaviess, Carroll and Stephenson counties. In JoDaviess county, a forest area was mis-labeled as prairie. The label was corrected. In Carrol county, a line between forest and prairie was missing. This line was added and incorrect lines were deleted. A prairie label was added to the resulting polygon. An adjacent forest larea was mis-labeled as prairie. This was corrected. In Stephenson county, several lines were removed. One line was added and several labels mis-identified as prairie were corrected to forest. The sixth set of corrections were made in Lake county. A color version of the plat maps were obtained and georeferenced, providing a clearer view of lines and labels. The primary changes were to ponds, streams, wetlands and bottomlands which were added or modified.

This two-year effort was partially funded by Illinois Department of Natural Resources, Office of Realty and Environmental Planning.

Land Code Value	Definition	Definition – Land cover label from the original plat map.
Ba	Bayou	A sluggish and stagnant stream that follows a winding course through alluvial lowlands, swamps, or river deltas.
Bl	Bluff, sand bluff	A high bank or bold headland, presenting a precipitous front; a steep cliff.
Bp	Brushy prairie
Br	Barrens, open barrens	A mixture of trees & grass, probably edge between timber & prairie.
Bt	Bottoms, bottom land	A lowland, usually highly fertile, along a stream; an alluvial plain.
Cl	Cliffs	A high, steep, or overhanging rock face.
Dg	Dry ground
Fa	Farm	A piece of land with houses, barns, etc., on which crops or animals are raised.
Fi	Field, enclosure	A piece of cleared land for crops of pasture.
Ft	Fallen timber	An area of downed timber, thought to be from diseases or insect infestations, high winds or tornado.
Gl	Glade	An open space in a forest.
Hi	Hills, sand hill	A natural raised part of the earth's surface, smaller than a mountain.
Hr	High ridge, sandy ridge	A long, narrow elevation of land.
In	Indian trace	Indian "improvements", such as villages, fortifications, mounds, clearings
Is	Island, sandy island	A land mass completely surrounded by water.
La	Lake	A large inland body of usually fresh water.
Le	Ledge	A projecting ridge of rocks.
Li	Licks	A deposit of exposed natural salt that passing animals lick.
Ll	Low land	A low and relatively level ground.
Ma	Marsh	A tract of low, poorly drained, soft land, permanently or semi-permanently water-covered, having aquatic and grass-like vegetation.
Mo	Mound, high mound	A low rounded natural hill, generally of earth, a knoll.
Or	Orchard	Land for growing fruit trees.
Pa	Pasture	Ground with grass, etc. used as food by grazing animals.
Po	Pond	A still body of water smaller than a lake.
Pl	Plantation	An estate, cultivated by workers living on it.
Pr	Prairie	A large area of level or rolling grassland, generally treeless.
Rg	Rough	Rugged overgrown ground.
Ri	River, wide river	A natural stream of water.
Rl	Rolling land
Ro	Rocky
Rv	Ravine, gully, valley, hollow	A low tract of land surrounded by hills, a small sheltered valley or basin, usually carved by running water, esp. in a rugged area.
Sa	Swale	A slight depression, sometimes swampy, in the midst of generally level land.
Sd	Sandy prairie, sandy ground	A large area of level or rolling grassland on sandy ground, generally treeless.
Sk	Sinkhole	A natural, circular depression in a land surface allowing subterranean passage.
Sl	Slough	A place full of soft, muddy waterlogged ground; a marsh or shallow undrained depression.
Sp	Spring	A flow of water from the ground.
Ss	Slash	Wet or swampy ground overgrown with brushes and trees.
Sw	Swamp	A wet, spongy area, permanently or semi-permanently covered with water, having shrubs and trees.
Th	Thicket	A thick growth of shrubs or small trees.
Ti	Timber, forest, grove, wooded	A thick growth of trees, etc. covering a large tract of land.
Wl	Wet land	Swamps or marshes
Wp	Wet prairie	A large area of level or rolling grassland, generally treeless, occurring on wet ground.

MAP Value	Definition	Definition – item used to dissolve land cover into 12 categories for mapping.
Barrens	Barrens, Open barrens	A mixture of trees & grass, probably edge between timber & prairie.
Bottomland	Bottoms, bottom land	A lowland with timber, usually highly fertile, along a stream; an alluvial plain.
Cultural	Farm, field, enclosure, Indian trace, orchard, pasture, plantation	A piece of land with houses, barns, etc., on which crops or animals are raised or grazed.
Forest	Timber, forest, grove, thicket, fallen timber	A thick growth of trees, etc. covering a large tract of land.
Marsh		A tract of low, poorly drained, soft land, permanently or semi-permanently water-covered, having aquatic and grass-like vegetation.
Other Wetland	Bayou, slash, swale
Prairie		A large area of level or rolling grassland, generally treeless.
Slough		A place full of soft, muddy waterlogged ground; a marsh or shallow undrained depression.
Swamp		A wet, spongy area, permanently or semi-permanently covered with water, having shrubs and trees.
Topographic, geographic		Bluff, sand bluff, cliffs, dry ground, glade, hills, sandy hill, mound, high mound, high ridge, sandy ridge, island, sandy island, ledge, licks, rough, rolling land, rocky, ravine, gully, valley, hollow, sandy ground, sinkhole
Water	lake, low land, pond, river, wide river, spring
Wet Prairie		A large, wet area of level or rolling grassland, generally treeless.

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Illinois Landcover in the Early 1800s

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Presettlement Land Cover - All Categories (MapServer)
Presettlement Land Cover - Map Categories (MapServer)

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