Digital version of 'Open-file report 92-181: geologic map of the Indian Spring quadrangle, San Bernardino County, California'

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Description This is a digital map database version of a previous U.S. Geological Survey Open-File Report, OF92-181. It contains 3 Arc/Info formatted coverages, distributed in Arc Interchange format, a plottable map representation of the database at 1:24,000 scale in
Originators Wilshire, Howard G.; Bedford, David R.; and Coleman, Teresa
Publication U.S. Geological Survey Open-File Report 02-272

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Overview of attributes

From their origin in ArcInfo and the Alacarte package, each
coverage contains topological and bookkeeping attributes of
little or no scientific interest; only the attributes of
scientific significance are described in detail here.  The
other attributes are AREA, PERIMETER, LENGTH, FNODE#, TNODE#,
LPOLY#, RPOLY#, cover#, cover-ID, SEL, and SYMB.
The primary layer is the geology layer (ind-geo), which
consists of both polygon features and arc features that
describes map units (polygons), and depositional contacts,
faults (which may or may not be polygon bounding features) and
map boundaries.
Map units (polygons) are described in the polygon attribute
table (ind-geo.pat).  The identities of the map units are
recorded in the PTYPE field by map label (i.e. Ts). For a
description of the map units, consult the PostScript or PDF
explanation pamphlets in this report.
Geologic lines (arcs) are recorded as strings of vectors and
are described in the arc attribute table (ind-geo.aat). They
define the boundaries of the map units, the faults, and the map
boundaries. These distinctions, including the geologic
identities of the unit boundaries, are recorded in the LTYPE
field. Attributes for geologic lines generally follow a scheme
of the type of geologic line (i.e. fault), followed by a
locational and/or scientific modifier (i.e. approx. located or
The geologic structure layer (ind-str) consists of point
features that describe geologic structures such as strike and
dip of beds.  Point features, typically structural
measurements, are described in the point attribute table (ind-
str.pat) and are used to represent locations of structural
measurements such as strike and dip, and foliation.  The type
of structural measurement of points is attributed in the PTTYPE
field, and the measurements taken at that location are
attributed in the STRIKE and DIP fields.
Features representing location of samples (ind-smp) discussed
in the original report, are described in the point attribute
table (ind-smp.pat).  Attributes of features in this dataset
are recorded in the PTTYPE field, and the sample number from
the map is recorded in the SAMPNO field.


Arcs with geological significance

Label Definition
LTYPE Description of the type of geologic line


Geologic units

Label Definition
PTYPE Geologic map unit attribute


Sample locations

Label Definition
pttype Description of the type of sample
sampno The sample number or designator as depicted on the map and in the report


Point Attribubes for the geologic structure layer, ind-str

Label Definition
PTTYPE Description of the structural measurement
Dip The dip value of the structural measurement, indeterminated dips contain a value of 99, assumed or inferred dip values are negative
Strike The strike of the structural measurement, based on the 'right hand rule'