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statement (EIS) being issued by the U.S. Fish and Wildlife 
Service in anticipation of seismic petroleum exploration 
in the wildlife refuge. The map will also serve as Plate 1 
in Landsat Assisted Environmental Mapping in the Arctic 
National Wildlife Refuge, by D.A. Walker, W. Acevedo, 
K.R. Everett, L. Gaydos, J. Brown, and P.J. Webber, to be 
published as a Special Report by the U.S. Army Corps of 
Engineers Cold Regions Research and Engineering Laboratory 
(CRREL), Hanover, N.H. The map has also been issued as 
USGS Publication 1-1443. Folded copies are available from 
the Western Distribution Branch, U.S. Geological Survey, 
Box 25286, Federal Center, Denver, Colorado 80225. The 
price is $2.50 each, postpaid to addresses in the U.S. and 
Canada. 
The map base is adapted from portions of four USGS 
1:250,000-scale topographic maps, Universal Transverse 
Mercator (UTM) Projection, 1927 North American Datum. The 
UTM rectangular grid is shown for Zones 6 and 7 at 50,000- 
meter and 10,000-meter intervals. The geographic grid is 
indexed by tick crosses every 15 minutes of latitude and 
30 minutes of longitude. Land lines and townships, 
numbered from the Umiat Meridian and Base Line, represent 
unsurveyed and unmarked protracted locations predetermined 
by the Bureau of Land Management. The 1955 magnetic 
declination varies from 33° to 36° East. 
The classification of vegetation and land cover is derived 
by machine processing of digital multispectral data 
comprising portions of three Landsat scenes, one of them 
from a Canadian receiving station. There are 12 cate 
gories. The CRREL report describes these in more detail 
and relates the categories to those in other vegetation 
classification systems in use for northern Alaska. 
For location control and area measurement, land cover 
classification is assigned to over three million map grid 
cells, each 50 x 50 m (0.25 ha or 0.6 acre) in the UTM 
rectangular coordinate system, Zones 6 and 7. The smallest 
unit of mapping is the Landsat pixel (0.46 ha), transformed 
to one of the map grid cells. Some generalization of land 
cover by spatial filtering has been attempted. Land cover 
area measurements for 12 classes and 89 townships are 
presented in acres and percent in a table printed on a 
back fold of the map. This facilitates comparison of the 
statistics with the corresponding areas on the map itself. 
To simplify map printing, the map cells for the two UTM 
zones were merged into one (Zone 6), and selected plani- 
metric features from the four component topographic maps 
were compiled into one new base map. To print the multi 
color digital map on a four-color printing press, two 
approaches using a large-format laser plotter were 
investigated. Both use the square raster unit of spatial 
information. One uses it also as a spatial unit for 
arranging halftone dots to achieve the multicolor effects 
from the four ink colors. The other uses the laser printer 
to simulate dot screens and angles directly onto the the 
color separation films (from which the printing plates are 
made) at the same time data are read from the spatial data