OTHER TX PROJECTS

• • Honey Creek Project
  • Jacob's Well Project
  • Geologic Atlas of Texas
  • Geodatabase Development
  • TX Gulf Coast Field Research Station Research
  • Big Bend
  • Big Thicket National Preserve
  • US/Mexico Border

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USGS Water Science Centers are located in each state.

Geologic Database of Texas: Project Summary, Database Contents, and User’s Guide

By Daniel K. Pearson

Contents: Overview | Project Summary | Database Contents | User's Guide

OVERVIEW

The Texas Geologic Atlas Project was first cited in the University of Texas - Bureau of Economic Geology (BEG) Report for 1961. In September of that year, compilation of the first of 38 Geologic Atlas of Texas (GAT) hardcopy map sheets began. The project, under the direction of Dr. Virgil E. Barnes, involved the work of 28 BEG geologists and many other geologists, seven cartographers, and several editors. The last GAT sheet was published in 1987, but the GAT has remained on the BEG "Best Seller" list of publications for many years and can be found at: http://www.beg.utexas.edu/mainweb/publications/pubs-bstsell.htm.

In October 2002, the United States Geological Survey (USGS), in cooperation with the Texas Water Development Board (TWDB), began development of an Environmental Systems Research Institute (ESRI) geodatabase model to capture the power of these data. Phase I (2002-2004) of this effort produced a library of 38 ESRI personal geodatabases representing the original 38 BEG Geologic Atlas of Texas map sheets. Phase II (2005-2006) involved the development of a Statewide Digital Geologic Atlas of Texas, combining the 38 personal geodatabases into one ESRI ArcSDE geodatabase containing more than 145,000 geologic features. Phase III (2007) continued to build on the work completed in the previous two phases with the inclusion of higher-resolution geologic data from the USGS STATEMAP program and on-going geodatabase refinement.

The final product is an ESRI personal geodatabase consisting of four feature datasets, corresponding to the four different resolutions of geologic data. Each feature dataset includes two feature classes: rock units and faults. Where available, other geologic feature classes may be included inside the scale-appropriate feature datasets (i.e. member units, geologic contacts, volcanic vents, etc.). This manual includes detailed information about the history of this project, description of the geodatabase contents, and a user’s guide for ArcGIS.

PROJECT SUMMARY

GAT Workgroup (2001-2002)

Formed in August 2001 by the Texas Geographic Information Council (TGIC), the GAT Workgroup consisted of federal, state and local GIS professionals interested in the development of a geologic GIS dataset for the State of Texas. The Workgroup was established to address the following items:
• Inventory all existing data, initiatives, and applications relative to the GAT.
• Achieve a consensus on digital standards for 1:250,000-scale surface geology data.
• Review existing data for compliance with consensus-based digital standards.
• Identify funding sources, data custodian, and future initiatives.

Meetings were held from September 2001 through February 2002. Agencies in attendance included representatives from: BEG, National Resource Conservation Service (NRCS), Texas Commission on Environmental Quality (TCEQ), Texas Parks and Wildlife Department (TPWD), US Army Corps of Engineers (USACE), USGS, Texas A &M University, and The University of Texas.

The GAT Workgroup discussed current (2001-2002) methods being employed in the creation of digital geologic data in Texas. In addition, the Workgroup distributed a survey to GIS professionals to investigate the utility of digital geologic data. More information about the GAT Workgroup can be found online at: http://www.dir.state.tx.us/tgic/committee/gat/.

Database Compilation (2002-2007)

Following the GAT Workgroup meetings in 2002, the USGS received funding to complete the first phase of this project using a cooperative agreement between the USGS and TWDB. This agreement has stood in place since that time, and the USGS and TWDB continue to modify and expand the scope of this project to keep up with the needs of data users and GIS professionals. The following sections detail the progress of that cooperative effort over the past five years.

Phase I – Digital Conversion (2002-2004)

The digital conversion of the original hardcopy map sheets began October 2002. Project planning among the USGS team established the need to utilize the ESRI personal geodatabase format for this process. This data format allowed for all the spatial data and attribute information (e.g. geologic time, formation descriptions) to be stored in a single database location.

The digital conversion included five main processing steps:
1. Pre-processing – All BEG map and scribe sheets were digitally scanned to TIFF format at 600 dpi.
2. Geo-referencing – The scanned images were then geo-referenced to a sheet-specific UTM projection using a network of 12 latitude/longitude locations. A Root Mean Square (RMS) error < 0.004 was attained for each map sheet.
3. Editing – Using advanced geographic editing techniques, the raster line work was converted to vector polylines and polygons.
4. Attribution – The geologic features were then attributed directly from the original hardcopy maps.
5. Symbology – A single ESRI Style file was built that universally symbolized all 38 personal geodatabase feature classes using symbols replicated from the original GAT maps.

Completed in September 2004, the results of this effort include:

• Library of 38 personal geodatabases representing each of the original BEG Geologic Atlas of Texas map sheets.
• ESRI Style file used to symbolize all Rock Unit and Member formations.
• FGDC-compliant metadata for all geographic datasets.
• QA/QC hardcopy documents delivered to cooperator for archive.

Phase II – Statewide Compilation (2005-2006)

In May 2005, work began on a statewide geologic dataset using the Digital Geologic Atlas of Texas library completed during Phase I of this effort. In order to accomplish this task, the USGS found it necessary to utilize the ArcSDE geodatabase model. This change in data format allowed for multiple-user editing, which increased production efficiency, and allowed for additional memory storage within the geodatabase.

In Phase II of this project, the USGS worked with geologists from TWDB, Peter George and Robert Bradley. The geologists reviewed the final data and assisted with Quality Assurance/Quality Control (QA/QC). Their main role was to identify discrepancies in the mapped geology, along boundaries between map sheets, and suggest modifications to the base geologic data. Using ESRI’s Data Reviewer, from the Production Line Toolset (PLTS), the USGS and TWDB shared a geodatabase containing error locations, recommendations, and date/time of final correction. The PLTS geodatabase of revisions was provided to TWDB for archive.

Completed in January 2006, the result of this effort was a statewide compilation of surficial geologic data housed in a single ArcSDE geodatabase containing:

• 117,000 Rock Unit polygons
• 16,000 Member Formations (polygon and line)
• 11,000 Faults
• 554 unique geologic symbols for the Seamless dataset
• Various sheet unique geologic formations (Vents, Dikes, Collapse Structures, others)

Phase III – Database Refinement and Expansion (2007)

In August 2007, the USGS began expansion of the previous geodatabase model to incorporate digital geology data of a higher than 1:250,000-scale. The data, developed by the BEG in cooperation with the USGS STATEMAP Program, were produced at several different resolutions, and mapped in various disconnected regions of the State. These downloaded data have been incorporated into the geodatabase with symbology and attributes where available. See website for more information: http://www.beg.utexas.edu/mainweb/services/GISdatabases.htm.

End-user feedback has also been incorporated into the database, after thorough review and approval. John Esteep (TCEQ-Geologist) provided guidance regarding the geologic age of the rock units at 1:250,000-scale. These recommendations have been included in the final product. In addition, the USGS was able to develop database relationships between the 1:250,000 rock unit features and their corresponding attribute records taken from the original map sheets.

Completed in December 2007, the final product is an ESRI personal geodatabase consisting of four feature datasets, corresponding to the four different resolutions of geologic data. Each feature dataset includes two feature classes: rock units and faults. Where available, other geologic feature classes may be included inside the scale-appropriate feature datasets (i.e. member units, geologic contacts, volcanic vents, etc.).

DATABASE CONTENTS

What is a geodatabase?

ESRI defines a geodatabase as collection of geographic datasets for use with ArcGIS. There are various types of geographic datasets, including feature classes, attribute tables, raster datasets, network datasets, topologies, and many others. With geodatabases, geographic data can be manipulated to represent the real world using a geographic information system (GIS) to produce maps, interactive queries, and various types of spatial analyses. The geodatabase is a framework behind which the geographic data can be used to create relationships among related spatial features.

Geodatabases commonly consist of one or more feature datasets, with multiple feature classes stored within each feature dataset. The feature dataset is the data container for feature classes that share single spatial reference. Feature classes contain spatial data, or geographic features, that share a single geometry type (i.e. polygon, polyline, point). In addition, geodatabases may contain attribute tables, which are made up of data elements arranged in row and columns. Relationship classes associate objects from the feature classes to records in an attribute table, or features in other feature classes.

Geodatabases come in several different ESRI formats. The personal geodatabase, backed by a Microsoft Access database, is intended for use in small groups and is limited to single-user editing for all geographic datasets. The ArcSDE geodatabase is more robust database, allowing large groups of users to access and edit the geographic data through version-based work flows. Both of these geodatabase formats were utilized for this project.

Geodatabase and Structure

The Geologic Database of Texas is an ESRI personal geodatabase consisting of four feature datasets, corresponding to the four different resolutions of geologic data. Each feature dataset includes two feature classes: rock units and faults. Where available, other geologic feature classes are included inside the scale-appropriate feature datasets (i.e. member units, geologic contacts, volcanic vents, etc.). Additionally, relationship classes and attribute tables are contained within the geodatabase, which enable the geographic features inside each feature class to be associated with the corresponding attribute table records.

Data available from Texas Water Development Board through: http://www.tnris.state.tx.us/
   

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