NOTE: This file contains transcribers notes to accompany the original README file (0readme.txt).

This data is a conversion product and should not serve as the primary source for the complete geologic information for this area. To obtain complete information, please go to https://pubs.er.usgs.gov/publication/i1509A.  This information may be found as referenced below:

Publisher:	U.S. Geological Survey	
Title:		Geologic and structure maps of the Wallace 1 degree by 2 degrees Quadrangle, Montana and Idaho
Author:		Harrison, J.E., Griggs, A.B., and Wells, J.D.
Original NGMDB identifier: 12251


Purpose: This file set is intended to make outdated Arc/INFO e00 files available as open-format shapefiles. No modification to files has been made. Projection was not changed. 

Process: e00 files were imported to coverage, then converted to shapefile using the ArcMap commands “Import from e00 (conversion)” and “Feature Class to Shapefile” respectively. Related tables were preserved by opening in ArcMap and exporting to txt.   

E00 files convert to:
	wal250k.e00 (principal Wallace line and polygon geologic map coverage0 = 
		wal250k_arc.shp
		wal250k_poly.shp
		wal250k.con.txt
		wal250k.lgu.txt
		wal250k.ref.txt
		wal250k.rlt.txt
		wal250k.ru.txt
		wal250k.st2.txt
	wal250bc.e00 (point coverage of breccia locations) =	
		wal250bc_point.shp
		wal250bc.ref.txt

Explanation of files, extracted from original metadata (wal250k.met)
      This GIS consists of two major and Arc/Info datasets: one
      line and polygon file (wal250k) containing geologic contacts
      and structures (lines) and geologic map rock units
      (polygons), and one point file (wal250bc) containing breccia
      outcrops.

      The "Geologic and structure maps of the Wallace 1- x 2-degree
      quadrangle, Montana and Idaho: a digital database" report
      (wal250k.pdf) contains a detailed description of each
      attribute code and a reference to the associated map symbols
      on the map source materials.  The database includes a geologic
      linework arc attribute table, wal250k.aat, that relates to
      the wal250k.con (contact look-up table), wal250k.st2
      (structure look-up table), wal250k.lgu (linear geologic unit
      look-up table), and wal250k.ref (source reference look-up
      table) files; a rock unit polygon attribute table,
      wal250k.pat, that relates to the wal250k.ru (rock unit
      look-up table) and wal250k.ref (source reference look-up
      table) files; and a breccia point attribute table,
      wal250bc.pat, that relates to the wal250bc.ref (source
      reference look-up table) files. 

Original files included:
	wal250k.met = metadata
	0readme.txt = readme
	wa_line.key = code key
	wa_line2.key = code key
	wa_point.key = code key
	wa_pol.key = code key

Modified: 24 August, 2023 by Karen Morgan, USGS contractor 



