This Directory contains the digital files for:

Digital Engineering Aspects of Karst Map :  A GIS version of  Davies, W.E., Simpson, J.H., Ohlmacher, G.C., Kirk, W.S., and Newton, E.G., 1984, Engineering aspects of karst:  U.S. Geological Survey, National Atlas of the United States of America, scale 1:7,5000. 

by Bret D. Tobin and David J. Weary
U.S. Geological Survey Open-File Report 2004-1352

Introduction

This data set was converted from a printed map to a digital GIS coverage to provide users with a citable national scale karst data set to use for graphic and demonstration purposes until new, improved data is developed. This data may be served on the internet or distributed freely, with proper citation. Because it has been converted to GIS format, this data can be easily projected, displayed and queried for multiple uses in GIS. The karst polygons of the original map were scanned from the stable base negatives of the original, vectorized, edited and then attributed with unit descriptions. All of these processes potentially introduce small errors and distortions to the geography. The original map was produced at a scale of 1:7,500,000; this coverage is not as accurate and should be used for broad-scale purposes only. It is not intended for any site-specific studies.

The data include GIS files in various ESRI formats.
A graphic file is also included for viewing and printing.

The data is projected to:

Albers conic equl area projection
North American Datum of 1983 
Standard_Parallel: 25.000000 
Standard_Parallel: 50.000000 
Longitude_of_Central_Meridian: -96.000000 
Latitude_of_Projection_Origin: 37.000000 
False_Easting: 0.000000 
False_Northing: 0.000000 

File structure and descriptions:

Readme.txt

kmetadata.htm (metadata file for karst polygons.)
smetadata.htm (metadata for subsidence areas arcs.)
karst.mxd (ArcGIS project file for viewing data. Created in ArcMap 8.3)

karst_thumbnail.jpg (low resolution image of karst in only the 48 contiguous states, 		no text included)

us_karst.pdf (graphic file of map data and text in Adobe Acrobat format. Acrobat 			Reader is available free on the internet. The map requires 36 inch (91 cm) paper for 		plotting at scale.)

data.zip/
	us_karstalb.mdb (personal geodatabase with karst polygon and subsidence area 				line data)

	covers/
		karst (karst polygon coverage)
		subside (subsidence area line coverage)
		us_states (polygon coverage of 1:1,000,000 U.S. state outlines)
	export/
		karst.e00 (karst polygons, ESRI export format)
		subside.e00 (subsidence areas arcs, ESRI export format)
	metadata/ 
		metadata files for both karst polygons and subsidence areas

	shapefiles/
		karst (karst polygons)
		subside (subsidence areas arcs)





This publication may also be found on the internet at:  http://pubs.usgs.gov/of/2004/1352/