GEOLOGY OF JOSHUA TREE NATIONAL PARK GEODATABASE

U.S. Geological Survey Open-File Report 2015–1175
By Robert E. Powell, Jonathan C. Matti, and Pamela M. Cossette

2015

The database in this Open-File Report was completed in cooperation with the National Park Service (NPS) and it has been shared with NPS, as a cooperating agency, in advance of formal publication.

README

This document serves to identify and describe the digital files that constitute this Open-File Report. Those files include geographic information system (GIS) software files that are accessible with Environmental Systems Research Institute (Esri) compatible, commercial GIS software. The data presented here were collected and compiled in support of the San Andreas Fault System in Southern California (SAFSOC) Project; the Basins and Landscape Coevolution (BALANCE) Project (closed) and the Southern California Areal Mapping Project (SCAMP) (closed) of the U.S. Geological Survey (USGS). These data comprise a rich collection of geologic observations and interpretations relevant to both the ongoing scientific interests of the USGS in southern California and the management requirements of NPS, specifically of Joshua Tree National Park (JOTR). This Open-File-Report benefitted greatly from scientific and technical reviews of the geodatabase and accompanying documents carried out by Evan Thoms (USGS, Alaska Science Center), Scott Graham (USGS, Cascade Volcanic Observatory), and Debra Block (USGS, Flagstaff Science Campus).

USGS OPEN-FILE REPORT CONTENTS

The JOTR GIS database comprises an Esri ArcCatalog 10.2 file geodatabase, a style sheet for working with structural data contained in the database, and supporting files including FGDC-compliant metadata and this Readme. For a more complete description of the data elements, we recommend that the reader examine the FGDC-compliant metadata.

Projection and coordinate information:

Projected Coordinate System:	NAD_1983_UTM_Zone_11N

Projection:	Transverse_Mercator

False_Easting:	500000.00000000

False_Northing:	0.00000000

Central_Meridian:	-117.00000000

Scale_Factor:	0.99960000

Latitude_Of_Origin:	0.00000000

Linear Unit: 	Meter


Geographic Coordinate System:	GCS_North_American_1983

Datum: 	D_North_American_1983

Prime Meridian: 	Greenwich

Angular Unit: 	Degree


Spatial geologic data are presented in an Esri file geodatabase v10.2.1, which consists of the following datasets, feature classes, and non-spatial data tables:

JOTR_OFR_v10-2.gdb

	Boundaries

		Neatline

		ParkBoundary

		Quadrangles_24k

		Quadrangles_100k

	Geology 

		Colluvium

		Contacts

		ContactsColluvium

		Dikes

		Faults

		GeologicUnits

		StructurePoints
	

Notes: The Contacts and Faults feature classes share lines only where faults form boundaries between geologic units. The Contacts and ContactsColluvium feature classes share lines only where the boundary between colluvial deposits and alluvial deposits is superposed on the boundary between bedrock and alluvial deposits. Because in the southern California desert, contacts are commonly exposed or locatable within the limits of the width of the lines plotted to represent the contacts, we attribute these lines as "observable" and represent them as solid lines. Where colluvial deposits mapped in the Colluvium feature class overlie line segments in the Contacts, Faults, and Dikes feature classes, those segments are attributed as concealed although the Colluvium polygons must be displayed to see the concealing unit.

In order to properly orient and view the structural point data in the feature class StructurePoints, the user must rotate the symbols.  In the Layers Properties dialog box, the user can go to the “Advanced” tab in the “Symbology” window. Choose “Rotate”, use the field “Symbol Azimuth” from the drop-down menu and “Geographic” rotation style to ensure correct orientation of the data. 
   

	Non-spatial data tables

		TblUnitDescriptionSummary

		TblParentUnitsSurficialProvenance

		TblParentUnitsArchLevelAssemblages

		TblParentUnitsMzBatholithicBelts

		TblParentUnitsBasementFramework

		TblBridgeToParentUnitsSurficialProvenance

		TblBridgeToParentUnitsBasementFramework

Note: The "BridgeTo" tables are readily converted to relationship classes.

Style sheet

This Open-File Report geodatabase includes a style sheet (but not an .mxd file) named JOTR_OFR_GeodatabaseStyle.style.

In order to apply the style, the user needs to open an ArcMap session and add the geology feature classes provided in the geodatabase. For the two polygon feature classes (GeologicUnits and Colluvium), the style file allows the user to readily apply a somewhat generalized version of our unit color scheme by right-clicking on the feature class and opening the "Properties" window, then opening the "Symbology" menu tab and following the appropriate "Categories" pathway to "Match to symbols in a style," to select the "MapUnitLabel" Value Field, and to browse to the style file we provide.

For line feature classes, the style file allows the user to display the FGDC standards for line weight and color for contacts, dikes, and faults by right-clicking on a feature class and navigating the “Properties” window to match symbols in the style by selecting the “StyleReference” Value Field.

For the point feature class, the provided style allows the user to properly orient and view the structural data in the geodatabase by right-clicking on a feature class and navigating the “Properties” window to match symbols in the style by selecting the “SymbolAzimuth” Value Field.

Please see the accompanying metadata for additional information.

Multiple data tables facilitate access to a broader regional analysis and to viewing assemblages of geologic units that may prove useful in land-use or resource management. To access unit data contained in the non-spatial object tables, the user can create joins, relates, or relationship classes. Please refer to the file named ofr20151175_data_table_map.pdf.