U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY

RECONNAISSANCE GEOLOGIC MAP OF THE DUNCAN CANAL/ZAREMBO ISLAND 
AREA, SOUTHEASTERN ALASKA

by Karl, S.M.(1), Haeussler, P.J.(1), and McCafferty, A.E.(2)

Digital preparation by Kelly Brunt(3)

1999

OPEN-FILE REPORT 99-168

U.S. Department of the Interior
Bruce Babbitt, Secretary

U.S. Geological Survey
Charles G. Groat, Director

(1) USGS, Anchorage, AK
(2) USGS, Denver, CO
(3) Raytheon STX contractor

DATABASE LIMITATIONS

This database is preliminary and has not been reviewed for conformity 
with U.S. Geological Survey editorial standards or with the North 
American Stratigraphic Code.  Any use of trade, product, or firm names 
is for descriptive purposes only and does not imply endorsement by 
the U.S. Government.


This database, identified as 'Reconnaissance geologic map of the 
Duncan Canal/Zarembo Island area, southeastern Alaska,' has been 
approved for release and publication by the Directory of the U.S. 
Geological Survey.  Although this database has been reviewed, the USGS 
reserves the right to revise the data pursuant to further analysis and 
review.  Furthermore, it is released on the condition that neither the 
USGS nor the United States Government may be held responsible for any 
damages resulting from its authorized or unauthorized use.

INTRODUCTION

Open-File Report 00-168 is a digital geologic data set that maps and 
describes the Duncan Canal-Zarembo Island area of southeastern Alaska.  
The map is a result of a multidisciplinary investigation of an area 
where an airborne geophysical survey was flown in spring 1997.  The 
USGS conducted field investigations in 1998 to identify and understand 
the source of the geophysical anomalies found in the airborne survey.

The digital geologic data set was created using ARC/INFO, version 7.2.1, 
a commercial Geographic Information System (GIS) designed by Environmental Systems Research Institute (ESRI), Redlands, California.  The geospatial 
data sets and associated files are available online at 

http://geopubs.wr.usgs.gov

The data set consists of the following ---

ARC/INFO coverages (in interchange file format):
dzgeol.e00       Polygon and line coverage showing geologic units 
                 and contacts (7.4mb)
dzfossil.e00     Point coverage of fossil data (100kb)
dzstruct.e00     Point coverage of structural data of bedding and 
                 foliations

Other files:
dzgeol_meta.faq   Metadata in 'frequently asked questions' format
dzgeol_meta.html  Metadata in html format
dzgeol_meta.txt   Metadata as a text file

DATABASE FILES
The geologic map data set consists of ARC/INFO coverages and INFO data 
tables that relate to the map features.  The coverages that comprise 
the data set consist of feature classes that include geologic lines 
(arcs), areas (polygons), and points.  See metadata (dzgeol_meta.txt) 
for detailed descriptions of structure and content.

Cover dzgeol contains both arc and polygon attributes.  Arcs define 
geologic contacts (stratigraphic or intrusive boundary, fault, or 
other linear feature) and are described in the arc attribute table, 
dzgeol.aat.  ARC-CODE is a numeric field which identifies the arc 
type, and LINE-TYPE is a text field which describes the numeric code.  
Extent of geologic units are defined by polygons and are described 
in the attribute table, dzgeol.pat.  Item CLASS is a numeric code 
to identify the geologic unit.  Items UNIT and DESC are text fields 
that describe the geologic unit.

Cover dzfossil contains points which locate fossil samples.  Fossil 
data (fossil identification, stratigraphic age, color alteration 
index, etc.) is stored in the point attribute table, dzfossil.pat.

Cover dzstruct is a point coverage containing the strike and dip 
data for measurements of bedding and foliations.  Items in the point 
attribute table, dzstruct.pat, include ANGLE, DIP, TYPE, LAT, LONG, 
and STATION.  The angle is measured azimuthally, with degree 0 pointing
North, and increasing in the clockwise direction.  The dip is 90 degrees 
clockwise from ANGLE.  Item TYPE identifies the measurement type.