Geologic Map Database of the El Mirage Lake Area, San Bernardino and Los Angeles Counties, California

Online link https://geo-nsdi.er.usgs.gov/metadata/open-file/00-222/metadata.faq.html
Description This geologic map database for the El Mirage Lake area describes geologic materials for the dry lake, parts of the adjacent Shadow Mountains and Adobe Mountain, and much of the piedmont extending south from the lake upward toward the San Gabriel Mountains
Originators Miller, David M. and Bedford, David R.
Publication U.S. Geological Survey Open-File Report 00-222

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Overview of attributes

This database consists of eight ARC/INFO format data sets (coverages), each of which is
considered a layer comprising a geologic map.  These layers are: a geology layer (elm-geol),
a geologic structure layer (elm-str), locations of spring mounds (elm-spr), locations of dated
samples (elm-kar), areas of previous mapping (elm-srcs), areas of mapping strategies
(elm-strat), locations of field observations (elm-obs), and a vector representation of a topographic map (elm-topo).

This Publication

Overview of attributes

The primary layer is the geology layer (elm-geol), 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
(elm-geol.pat).  The identities of the map units are recorded in the PTYPE field by map label (i.e. Qvof).
For a description of the map units, consult the PostScript or PDF explanation pamphlets in this report.
Areal features in the geology layer (ELM-GEOL) that require attributes other than a map unit, are given
unique identification numbers in the ITEMID field.  ITEMID provides a common field to which other
tabular data (ELM-GEOL.PID) can be used in a relational database.
Geologic lines (arcs) are recorded as
strings of vectors and are described in the arc attribute table (elm-geol.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
queried).

This Publication

Overview of attributes

The geologic structure layer (elm-str) consists of arc and point features that describe geologic structures such as strike and dip of beds, and fold axis.  Arc features are described in the arc attribute table (elm-str.aat), and in this report only describe linear representations of fold axis and lineaments interpreted from air photography.  The type of linear structural feature is distinguished in the LTYPE field.  Point features are described in the point attribute table (elm-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.

This Publication

Overview of attributes

Point features representing location of spring mound deposits (elm-spr) are described in the point attribute table (elm-spr.pat).  Attributes of features in this dataset are recorded in the PTTYPE field.

This Publication

Overview of attributes

Point features representing location of Potassium/Argon (K/Ar) dated samples (elm-kar) are described in the point attribute table (elm-kar.pat).  Attributes of features in this dataset are recorded in the PTTYPE field.

This Publication

Overview of attributes

An index of previous mapping (ELM-SRCS) consists of four ARC/INFO regions: PREVMAP1, PREVMAP2, PREVMAP3, and PREVMAP4.  ARC/INFO regions allow polygonal information to be stored in a way that areas, or regions, can be overlapping, or non-contiguous in nature.  Attribute information for regions is stored in tables that have the name of the coverage Polygon Attribute Table (PAT), followed by the name of a region (i.e. elm-srcs.patprevmap1).  Regions may have different table definitions (items) than the base Polygon Attribute Table, and regions within the same coverage may have different table definitions (items). Each region has identical table definitions, consisting of the following items: AUTHORS, YEAR, TITLE, PUBLICATION, and SCALE.  The Polygon Attribute Table (ELM-SRCS.PAT) has no attributes with the exception of the default ARC/INFO attributes.  For complete bibliographic references, see appendix 1 in the geologic discussion of this report.

This Publication

Overview of attributes

Mapping strategies used by the authors of this report (ELM-STRAT) are represented as polygons.  The mapping strategies are described in the Polygon Attribute Table (ELM-STRAT.PAT) for this coverage.  The mapping strategies are described in the following items: FIELDID, GEOLOGIST, and METHODS.

This Publication

Overview of attributes

Point features representing location of field observations made by the authors of this report.  Attributes of features in this dataset are recorded in the PTTYPE field in the point attribute table (elm-obs.pat).  There is only one attribute in this field: Field Observation

This Publication

elm-geol.aat

Arc attributes for coverage 'elm-geol' (Faults, depositional contacts, and rock units)

Label Definition
LTYPE Description of the type of geologic line

elm-geol.pat

Polygon attributes for coverage 'elm-geol' (Faults, depositional contacts, and rock units)

Label Definition
PTYPE Geologic map unit labels are typically short sequences of letters, in which the first letter, which is commonly capitalizzed, indicates the geologic period in which the unit was formed. The correspondence between these labels and the descriptions of the units themselves is specified in the accompanying geologic report and on the printed map sheet.
ITEMID Provides a common field to which other tabular data (ELM-GEOL.PID) can be used in a relational database

elm-str.aat

Arc features in coverage 'elm-str' (Geologic structure layer - strike and dips, fold axis, etc)

Label Definition

elm-str.pat

Point features in coverage 'elm-str' (Geologic structure layer - strike and dips, fold axis, etc)

Label Definition

elm-spr.pat

Point Features in the coverage 'elm-spr' (Location of spring mound deposits)

Label Definition

elm-kar.pat

Point Features in the coverage 'elm-kar' (locations of dated samples)

Label Definition

elm-srcs

An index of previous mapping

Label Definition

elm-strat

Mapping strategies used by the authors of this report

Label Definition

elm-topo

Vector representation of a topographic map for the mapped area

Label Definition

elm-obs

Point Features in the coverage 'elm-obs' (locations of field observations)

Label Definition