This file contains ESRI ArcView shape files and grids used to compile Minnesota 
Geological Survey, Miscellanceous Map Series Map M-120 Superimposed Magnetic on Gravity Anomaly 
Map of the Duluth Complex and Related Rocks, Northeastern Minnesota, by Val W. Chandler.  The zip file 
was created with WinZip 7.0 on NT4.0.  The shape files and grids are compiled in an ArcView 3.x project 
file entitled m120smog.apr.  Note: Although the gravity and magnetic data are shown superimposed, the 
grids are available in the project for viewing or use as separate themes. The publication scale of the map is 
1:100,000.  It is not recommended that the data be used at larger scales.  Printing of the ArcView files may 
be very lengthy (over 24 hours at 300 dpi and will require a 42 inch wide plotter).  The jpeg file will print 
however.  Although the text from the jpeg is reduced in quality, the image prints well.

ESRI Spatial Analyst is a required ArcView extension to open the project file.

An image of the map plate is also provided.  This image was created at a resolution of 
144 dpi and depending upon the viewing software may not print at a 1:100,000 scale. We printed the jpeg 
with software called ZEHRaster Plus, which came with the HP plotter.

Metadata is provided in Acrobat Reader PDF format.

The map presents derivative-enhanced aeromagnetic (gray scale) and gravity (color scale) data for the 
Duluth Complex and environs.  A presentation of this type showing two discrete data sets is called a 
Superimposed Magnetic on Gravity (SMOG) map.  These data are used in geologic mapping to trace 
density and magnetization variations in the near-surface bedrock.  Accordingly, these derivative data were 
used in conjunction with outcrop and drill-hole data to compile a bedrock geologic map of the area.  This 
map published as Geologic Map of the Duluth Complex and Related Rocks, Northeastern Minnesota by 
Miller, J.D., Jr., Green, J.C., Severson, M.J., Chandler, V.W., and Peterson, D.M., 2001.  This map is a 
compilation of new and pre-existing geologic data acquired over the past 40 years. Digital files in 
ArcView® format containing rock-unit polygons, line symbols, and attribute tables for the polygons and 
line symbols are available at ftp://156.98.153.1/pub2/m-119/.

Shape file and grid naming:  All files with clp or clpd indicate locations extracted from larger file.

Project file:  cdulsmog
	View1 – SMOG map and base
	View 2 – Location map
	Layout – SMOG map layout

Shape files in directory
	mgd150cl – aeromagnetic grid, the aeromagnetic grid used for the superimposition.
	bsan.xxxxtext – annotation themes for base (trs, latlon, rivers, lakes cities, counties)
	cntylins – county line
	zerogdcntr – zero contour line from the gravity grid
	grvpts – gravity stations within study area
	lakes – lake outlines
	majrrds – major road lines
	minorrds- minor road lines
	papgwlk – study area outline showing full county lines into Lake Superior
	railroads – railroad lines
	rivers – river lines
	plsnet – Township, range, section lines
	ggd6clp – gravity grid used for color-fill contour map


Other files:

readme.txt –  introduction to the map and digital files.
m120smog.jpg – JPEG image of the entire map plate at a resolution of 144 dpi.
m120metadata – metadata about the major themes in the A.V. project.

Info Folder – required ArcView files for A.V. use.