Minnesota Geological Survey

M-126, Bedrock Topographic and Depth to Bedrock Maps of the Western Half of the Mesabi Iron Range, 
Northern Minnesota

Compiled and authored by 

M.A. Jirsa, D.R. Setterholm, B.A. Bloomgren, and R.S. Lively

2002

The data and results of the project analysis are presented as ArcView Shape files that are compiled within 
an ArcView project entitled m126.apr.  All of the map and plate files are included. The zipped files can be unzipped, using the WinZip 
program available on the Internet, to other drives and retain their original read/write permissions.

A copy of the zipped files and the unzipped project can also be obtained on a CD by contacting the MGS 
Map Sales office at 612-627-4780, ex. 238.  A paper plot of the map plate can also be obtained.

Be aware that the ArcView project m126.apr requires the ArcView extensions Spatial Analyst and  
3-d Analyst to open and properly display the map plates in ArcView.  The metadata for various 
grids, lines and shapefiles in the project may be viewed as html files within themetadata folder in the 
m-126 folder.

A list of the files in the project is given below:

Folder: m-126

	m126.apr
	Shape Files:

		Common to all views:
			graphicstmp—latlong tics
			trclpd – township and range lines with labels
			trsclpd – section lines with corners labeled

		Bedrock Topography view
			grid10-Bedrock Topography Shaded-Relief grid—restructured elevation data in program 
TopoShade to create shaded relief map of the pre-mining bedrock surface.
			btgdfromtin-Bedrock topography grid—elevation grid with 30 meter cell size of the bedrock 
surface.
		
		Database view
			glg83clp-geology polygons showing bedrock geology contacts and labels.
			exploration drillholes.shp-Exploration drillholes—drillhole data collected from agency and 
company files
			outcropclpd.shp-Outcrop locations—data collected from new field work and existing maps and 
reports
			water well locations.shp-Water well locations—data on water wells from CWI at MGS.	

		Depth to Bedrock view
			dtgdclpd-Depth to bedrock grid—grid of elevation values representing depth to bedrock
			outcropclpd.shp-Outcrops—data collected from new field work and existing maps and reports
			ovrbdrn_thickln.shp-Depth to bedrock lines—isolines separating polygons of different depths to 
bedrock surface
			
		Location of Study Area view
			newpagp.shp-Study area outline—area covered by the bedrock topographic and depth to 
bedrock mapping.
			mncomdt.shp-Mn county outlines—polygon file of Minnesota Counties.  Metadata can be 
obtained for county data from the Dept. of Natural Resources Data Deli at 
http://deli.dnr.state.mn.us/metadata/index_th.html

	Folders:
		btgdfromtin – grid of bedrock surface elevation values
		drgs – topographic maps for use in ArcView, in USGS digital raster graphics format (DRG)
		dtgdclpd – grid of overburden thickness from which the depth-to-bedrock map was created
		grid10 – grid from which the bedrock topographic shaded-relief map was created
		info – Arc info files required by ArcView to use the grids
		
		metadata – metadata about the shape files in the project.  (btgd-bedrock topography grid; dtgd-depth to bedrock grid; expldh-exploration 
drillholes; dtln- depth to bedrock lines; outcrop-outcrop locations; btshd-bedrock topography shaded-relief 
map).  CWI water well metadata is provided in Word 97 format as Cwiver4.doc. mgsattribute.pdf—metadata about MGS attributes used in some of the data tables
			
The directory LCMR_rpt contains a pdf file of the Final Report for the 2000 LCMR Iron Range project 
completed by the MGS.