Lyndon B. Johnson 

National Historical Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/024 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
ON THE COVER: 

The cattle on the LBJ Ranch are descended from the same bloodline as the herd that Lyndon Johnson 

owned. They look more like 1960s Hereford cattle and so they can be called "history on the hoof." 

Lyndon B. Johnson National Historical Park Web site (www.nps.gov/lyjo, accessed 1/23/2008). 

NPS Photo 
Lyndon B. Johnson National Historical Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/024 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

January 2008 

U.S. Department of the Interior 

Washington, D.C.
The Natural Resource Publication series addresses natural resource topics that are of interest 

and applicability to a broad readership in the National Park Service and to others in the 

management of natural resources, including the scientific community, the public, and the NPS 

conservation and environmental constituencies. Manuscripts are peer- reviewed to ensure that 

the information is scientifically credible, technically accurate, appropriately written for the 

intended audience, and is designed and published in a professional manner. 

Natural Resource Reports are the designated medium for disseminating high priority, current 

natural resource management information with managerial application. The series targets a 

general, diverse audience, and may contain NPS policy considerations or address sensitive 

issues of management applicability. Examples of the diverse array of reports published in this 

series include vital signs monitoring plans; "how to" resource management papers; 

proceedings of resource management workshops or conferences; annual reports of resource 

programs or divisions of the Natural Resource Program Center; resource action plans; fact 

sheets; and regularly- published newsletters. 

Views and conclusions in this report are those of the authors and do not necessarily reflect 

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not constitute endorsement or recommendation for use by the National Park Service. 

Printed copies of reports in these series may be produced in a limited quantity and they are 

only available as long as the supply lasts. This report is also available from the Geologic 

Resource Evaluation Program website (http://www2.nature.nps.gov/geology/inventory/

gre_publications) on the internet, or by sending a request to the address on the back cover. 

Please cite this publication as: 

Thornberry- Ehrlich, T. 2008. Lyndon B. Johnson National Historical Park Geologic Resource 

Evaluation Report. Natural Resource Report NPS/NRPC/GRD/NRR—2008/024. National 

Park Service, Denver, Colorado. 

NPS D- 83, February 2008 
 LYJO Geologic Resource Evaluation Report iii

Table of Contents 

List of Figures .............................................................................................................. iv

Executive Summary ...................................................................................................... 1

Introduction ................................................................................................................... 2

Purpose of the Geologic Resource Evaluation Program ............................................................................................2

Geologic Setting .........................................................................................................................................................2

Geologic Issues............................................................................................................. 4

Groundwater Movement .............................................................................................................................................4

Surface Water Movement...........................................................................................................................................4

Sediment Load and Channel Storage.........................................................................................................................4

General Geology ........................................................................................................................................................5

Geologic Features and Processes............................................................................... 6

Geology and History Connections ..............................................................................................................................6

Llano Uplift..................................................................................................................................................................6

Geology and Biology Connections..............................................................................................................................7

Map Unit Properties .................................................................................................... 11

Map Unit Properties Table........................................................................................................................................12

Geologic History.......................................................................................................... 15

Glossary....................................................................................................................... 21

References................................................................................................................... 23

Appendix A: Geologic Map Graphic .......................................................................... 26

Appendix B: Scoping Agenda and Notes.................................................................. 29

Attachment 1: Geologic Resource Evaluation Products CD 
 NPS Geologic Resources Division iv 

List of Figures 

Figure 1. Map of Texas showing physiographic provinces.............................................................................................3

Figure 2. Historic structures at Lyndon B. Johnson National Historical Park..................................................................8

Figure 3. Geologic time scale.......................................................................................................................................17

Figure 4. Map showing Ouachita tectonic front ............................................................................................................18

Figure 5. Diagram showing the evolution of the Ouachita highland during Mesozoic rifting.........................................19

Figure 6. Map showing structural features in the area of Lyndon B. Johnson National Historical Park........................20
 LYJO Geologic Resource Evaluation Report 1

Executive Summary 

This report accompanies the digital geologic map for Lyndon B. Johnson National 

Historical Park in Texas, which the Geologic Resources Division produced in collaboration 

with its partners. It contains information relevant to resource management and scientific 

research. 

Lyndon B. Johnson National Historical Park 

commemorates the reconstructed birthplace, boyhood 

home and ranch of the 36th president, as well as the Texas 

Hill Country ranch lifestyle while also protecting part of 

the Pedernales River drainage basin. The park lies in an 

area of central Texas known as the Llano Uplift, which 

has the metamorphic core of an ancient mountain range, 

Paleozoic and Mesozoic sedimentary rocks, and recent 

alluvial, terrace, and colluvial deposits. 

Rock structure and geomorphological (surficial) 

processes have played a prominent role in the history of 

the entire central Texas Hill Country, impacting early 

settlement, mining activity, and cattle ranching. Geologic 

processes gave rise to rock formations, mountains and 

valleys, dissected plateaus, mineral deposits, and broad 

river plains. Knowledge of the geologic features and 

processes directly influences resource management 

decisions in the park. Natural resource issues identified 

by the park include: air and water quality, groundwater 

movement, archaeological excavations, flood risk, 

wildlife populations, research projects, interpretive 

needs, and economic resources. 

The richness of geological, historical, and cultural 

resources in Lyndon Johnson National Historical Park 

may be important for land- use planning and in planning 

for visitors in the park. A detailed geologic map of the 

park, wayside exhibits, and a road or trail log would 

provide information helpful to visitor appreciation of the 

geologic history and dynamic processes that created the 

natural landscape. These information products would 

also serve to emphasize the long history showcased at the 

park. 

Human activities have played a significant role in 

determining the surficial features of the park and have 

also affected ecological responses to changes. Cattle 

grazing has changed riparian zones, and dams have 

interrupted water and sediment flow. The dynamic 

system may show noticeable change within a human life 

span. 

The following geologic features, issues, and processes are 

significant for management of the park: 

• Groundwater movement. Lyndon B. Johnson National 

Historical Park is located within the Pedernales river 

Valley. The Pedernales river and its associated 

hydrogeologic system are primary resources of the 

park. Understanding how water moves through the 

subsurface is vital for resource management. 

The valley is floored with thick alluvium and terrace 

deposits containing several shallow aquifers. Wells 

into these aquifers and other bedrock aquifers provide 

water to the community. Groundwater inflow is an 

important contributor to the water budget of the river 

in the valley. A working model of the hydrogeologic 

system within the park would be helpful to predict 

environmental responses to contaminants and to 

remediate affected areas. 

• Surface Water Movement. The Pedernales River is an 

important tributary of the Colorado River. It cuts 

through the Llano Uplift, dissecting plateaus and 

exposing the ancient roots of the Ouachita Mountains. 

Intense seasonal precipitation and high runoff cause 

flooding along the river. This flooding threatens many 

of the historical structures and features of the park. 

The water quality of the river system is threatened by 

agricultural waste and sediment loading from erosion 

and runoff. 

• Sediment Load and Channel Storage. Erosion along 

the riverbanks in the area increases the sediment load 

carried by streams and exposes aquatic ecosystems to 

contamination trapped in sediments. Sediment loading 

can change channel morphology and increase the 

frequency of overbank flooding. Mostly fine- grained 

sediments transport contaminants in this water 

system. Movement of these sediments follows a 

seasonal cycle with increased flow following storms 

and spring runoff. 

• General Geology. The unique geology of the Llano 

Uplift has been and continues to be the focus of 

interest and research. More research in the park area 

would improve understanding of local geologic 

features and processes. 
 NPS Geologic Resources Division 2 

Introduction 

The following section briefly describes the National Park Service Geologic Resource 

Evaluation Program and the regional geologic setting of Lyndon B. Johnson National 

Historical Park. 

Purpose of the Geologic Resource Evaluation Program 

The Geologic Resource Evaluation (GRE) Program is 

one of 12 inventories funded under the NPS Natural 

Resource Challenge designed to enhance baseline 

information available to park managers. The program 

carries out the geologic component of the inventory 

effort from the development of digital geologic maps to 

providing park staff with a geologic report tailored to a 

park’s specific geologic resource issues. The Geologic 

Resources Division of the Natural Resource Program 

Center administers this program. The GRE team relies 

heavily on partnerships with the U.S. Geological Survey, 

Colorado State University, state surveys, and others in 

developing GRE products. 

The goal of the GRE Program is to increase 

understanding of the geologic processes at work in parks 

and provide sound geologic information for use in park 

decision making. Sound park stewardship relies on 

understanding natural resources and their role in the 

ecosystem. Geology is the foundation of park 

ecosystems. The compilation and use of natural resource 

information by park managers is called for in section 204 

of the National Parks Omnibus Management Act of 1998 

and in NPS- 75, Natural Resources Inventory and 

Monitoring Guideline. 

To realize this goal, the GRE team is systematically 

working towards providing each of the identified 270 

natural area parks with a geologic scoping meeting, a 

digital geologic map, and a geologic report. These 

products support the stewardship of park resources and 

are designed for non- geoscientists. During scoping 

meetings the GRE team brings together park staff and 

geologic experts to review available geologic maps and 

discuss specific geologic issues, features, and processes. 

Scoping meetings are usually held for individual parks 

and on occasion for an entire Vital Signs Monitoring 

Network. The GRE mapping team converts the geologic 

maps identified for park use at the scoping meeting into 

digital geologic data in accordance with their innovative 

Geographic Information Systems (GIS) Data Model. 

These digital data sets bring an exciting interactive 

dimension to traditional paper maps by providing 

geologic data for use in park GIS and facilitating the 

incorporation of geologic considerations into a wide 

range of resource management applications. The newest 

maps come complete with interactive help files. As a 

companion to the digital geologic maps, the GRE team 

prepares a park- specific geologic report that aids in use 

of the maps and provides park managers with an 

overview of park geology and geologic resource 

management issues. 

For additional information regarding the content of this 

report and up to date GRE contact information please 

refer to the Geologic Resource Evaluation Web site 

(http://www2.nature.nps.gov/geology/inventory/). 

Geologic Setting 

Lyndon B. Johnson, the 36th president, grew up in the 

Texas Hill Country. Lyndon B. Johnson National 

Historical Park preserves his LBJ Ranch and Johnson 

City districts, covering 1,570 acres (674 acres federal). 

The park was designated a national historic site on 

December 2, 1969, and redesignated a national historical 

park on December 28, 1980. The Johnson family, which 

can trace its Texas Hill Country lineage several 

generations back has been generous in donating land to 

the park. 

Today the ranch is preserved as a working ranch in the 

style of the 1960s, with about 100 to 125 head of whitefaced, registered Hereford cattle. In the Johnson 

Settlement, the park maintains a small herd of Longhorn 

cattle and horses. Gazing is highly regimented and 

closely- monitored according to a livestock management 

and grazing program. There is strict control over 

livestock numbers at the park. 

The ranch protects vital habitat and pasture land along 

the Pedernales River Valley near the community of 

Stonewall, Texas. Here the Pedernales River flows 

through Blanco and Gillespie counties as it heads 

eastward towards its confluence with the Colorado 

River. The river is part of the larger Colorado River basin 

(Kier 1988). This area is situated near the boundary 

between the Edwards Plateau and Central Texas Uplift 

physiographic provinces (fig. 1). The province contains a 

collection of tablelands heavily dissected by canyons 

along entrenched streams. Local tributaries relevant to 

the two districts of the park include Wittington Creek 

and Town Creek, as well as a number of seasonal, 

unnamed washes and streams. 

The topography of the Pedernales River Valley ranges 

from rugged, rough terrain to rolling hills of considerable 

relief with elevations ranging from 305m to 760 m 

(1,000ft to 2,500 ft) above sea level. The river drains 3,372 

km2 (1,302 mi2

), of which 1,559 km2 (602 mi2) is upriver 

from the park. Large, relatively flat floodplains flank the 

river. The river cuts through the Llano Uplift of central 

Texas, a geologic feature containing the metamorphic 

and igneous crystalline core of an ancient collisional 

orogenic belt that formed during the Precambrian 

(Mosher and Levine 2005). This structural high 
 LYJO Geologic Resource Evaluation Report 3

dominates the area. However, erosion since Cretaceous 

time has resulted in little topographic expression. 

Sharp bluffs are common where Cretaceous rocks rim 

the Llano Uplift (Kier 1988). The uplift is bounded on the 

south and west by the Edwards Plateau and on the east 

by an area known as the central Texas Hill Country. 

These hills are formed by the intense erosion of 

Cretaceous limestone capping uplands of sandstone and 

shale. 

Figure 1. Map of Texas showing physiographic province sections. Lyndon B. Johnson National Historical Park is near the boundary

between the Edwards Plateau and Central Texas Uplift provinces. Modified from map by the Bureau of Economic Geology at the 

University of Texas at Austin (1996) in the Perry-Castañeda Library Map Collection. Graphic by Trista L. Thornberry-Ehrlich (Colorado 

State University). 
 NPS Geologic Resources Division 4 

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Lyndon B. Johnson 

National Historical Park on May 15, 2003, to discuss geologic resources, address the 

status of geologic mapping, and assess resource management issues and needs. The 

following section synthesizes the scoping results, in particular those issues that may 

require attention from resource managers. 

Groundwater Movement 

The broad Pedernales River valley of the upper Colorado 

River drainage is floored with thick Quaternary alluvium 

and colluvium, unconsolidated terrace deposits, and 

fractured Cretaceous sedimentary rocks. Shallow 

aquifers are developed in these mixed units in the 

Lyndon B. Johnson National Historical Park area. Some 

fractured bedrock supplies water to the system locally as 

springs and seeps. Groundwater flow responds to 

variations in seasonal precipitation and is largely from 

upland areas toward the baseline of the Pedernales River. 

Groundwater flow generally follows the topographic 

surface, typically flowing toward the nearest stream or 

river. 

Unconsolidated units may be as much as 21 m (69 ft) 

thick beneath some parts of the valley floor. Coarsegrained beds and lenses of sand and gravel are often 

permeable and productive aquifers, whereas finegrained beds of clay and silt are not. If the 

unconsolidated deposits are part of a stream terrace, 

water discharge is typically toward adjacent stream 

valleys into alluvium. 

For park staff to understand the hydrogeologic system at 

the park, they need to know how water travels through 

the subsurface to predict hydrologic responses to 

contaminants and agricultural wastes. The movement of 

nutrients and contaminants through the hydrogeologic 

system can be modeled by monitoring system inputs, 

such as rainfall, and outputs, such as streamflow. Other 

input sources include wind, surface runoff, groundwater 

transport, sewage systems, landfills, and fill dirt. Streams 

integrate groundwater flow and surface runoff of the 

watershed. Thus, they provide a cumulative measure of 

the status of the watershed’s hydrologic system. 

Consistent measurement of these parameters is crucial to 

establishing baselines for comparison. 

Inventory, Monitoring, and Research Needs for Groundwater 

Movement 

• Define the influences of bedrock and topography on 

local watersheds at Lyndon B. Johnson National 

Historical Park. 

• Map and quantify subterranean water recharge zones. 

• Map and monitor water quality at all known springs 

and seeps. 

• Install monitoring stations to measure atmospheric 

inputs of important chemical components (such as 

nitrogen, mercury, and pH) and outputs to 

groundwater. 

• Investigate additional methods to characterize 

groundwater recharge areas and flow directions 

Surface Water Movement 

The Pedernales River watershed covers approximately 

3,372 km2

 (1,302 mi2). Understanding the dynamics behind 

surface water movement in the area is essential for 

resource management. The transport of sediments and 

contaminants is controlled by the supply and input rates 

of the material and by the downstream transport of water 

and sediment, especially during peak flow. 

The average annual precipitation in the Pedernales River 

watershed is greater than 81 cm (32 in.). Most of this 

precipitation occurs in winter and spring. Intense 

seasonal precipitation and/or high runoff storms cause 

flooding along the Pedernales River. 

The bed of the Pedernales River is bedrock and large 

cobbles. In the park, the river meanders through 

unconsolidated valley fill from cut banks to point bars, 

simultaneously eroding from the former and depositing 

mixed sediments on the latter. 

Inventory, Monitoring, and Research Needs for Surface 

Water Movement 

• Determine how surface water movement is affected by 

surficial deposits and soils. 

• Monitor discharge, pH, specific conductance, 

temperature, dissolved oxygen, and nitrate 

concentration in surface water of the park. 

• Monitor streamflow, including seasonal mean flows, 

lowest flow rates, and timing and magnitude of storms. 

• Investigate paleoflood hydrology. 

Sediment Load and Channel Storage 

Erosion in the Pedernales River watershed increases the 

sediment load carried by streams. Sediment loads and 

distribution affect aquatic and riparian ecosystems, and 

sediment loading can result in changes to channel 

morphology and increase the frequency of overbank 

flooding. 

Suspended sediment load is a resource management 

concern because it can contaminate drinking water 
 LYJO Geologic Resource Evaluation Report 5

sources (both surface and groundwater) and increase 

concentrations of toxic chemicals, such as fertilizers and 

other agricultural wastes trapped in river bottom 

sediments. However, fine- grained sediments are also 

vital in the overall fluvial transport of contaminants in a 

water system. Some pesticides and other contaminants 

bond to soil and fine- grained particles that are then 

eroded and transported downstream (Anderson et al. 

2002). Thus, sediments act as sources and sinks for 

contaminants (Breuninger 2000). 

The amount of material being transported by the 

Pedernales River depends on the flow conditions and 

overall hydrologic energy. During seasonally high flows, 

the river probably transports pebbles and gravel as 

bedload and sand and finer- grained particles in 

suspension (Smith et al. 1998). These materials are 

typically deposited as migrating downstream point bars. 

Channel storage of fine sediment along with the 

contaminants follows a seasonal cycle. The cycle is 

subject to hydrologic variability with increased exposure 

of sediments to movement during spring runoff and 

decreased sediment movement in autumn. 

Fine- grained sediments do not travel downstream in a 

single pulse but are commonly deposited on the bottom 

and then picked up again (Miller et al. 1984). This 

intermittent transport of contaminants and fine- grained 

sediment increases the area affected by contamination. 

Three dams in the park 0n the Pedernales River impound 

water for crop irrigation and for scenic purposes. Two of 

the dams, the Jordan and Johnson dams, are maintained 

in accordance with NPS management guideline, NPS40, “Dams and Appurtenant Works: Maintenance, 

Operations, and Safety.” Resource managers should be 

aware of the effects of sediment loading and of any 

stored contaminants that results from hydrologic 

disturbances of the sediments trapped behind these 

structures. 

Inventory, Monitoring, and Research Needs for Sediment 

Load and Channel Storage 

• Assess hydrologic conditions to identify actual and 

potential “problem areas” (near roadways, trails, the 

Visitors’ Center, and administrative facilities) for 

prioritized monitoring. Monitor problem areas with 

repeated aerial photography. 

• Measure morphologic change in stream channels 

related to sediment load. Reliable measurements 

generally require three to five cross sections over 

several hundred meters (yards) of channel. 

• Promote cattle- free riparian zones along the river 

corridor to reduce stream bank erosion and loss of 

pastureland. 

• Use shallow (25- cm, or 10- in.) and deeper core data to 

monitor rates of sediment accumulation and erosion 

and analyze changes in chemical constituents of 

sediments. 

• Cooperate with local agencies to determine amounts, 

types, and durations of exposure of the watershed to 

contaminants. 

• Correlate watershed disturbance with sediment load in 

streams and any reduction in aquatic biological 

productivity. 

General Geology 

The unique geology of the Llano Uplift has sparked 

research interest among geologists. More local research 

would help resource managers at the park understand 

the relationships among various physical factors in the 

ecosystem. 

In addition to general research, the function of the park 

as a working ranch requires careful management of the 

pasturelands necessary for cattle grazing. Erosion is 

removing these pasturelands, and overgrazed areas are 

especially at risk due to loss of stabilizing vegetation. 

Inventory, Monitoring, and Research Needs for General 

Geology 

• Determine the depth of alluvial fill to bedrock along 

the Pedernales Creek bottom. 

• Map the geomorphology of the park. 

• Study remediation techniques to restore pastureland 

along vulnerable reaches of the Pedernales River and 

along steep slopes. 

• Study geologic controls on the restoration of prairie 

lands and native soils. 

• Study historical land use, such as Native American 

sites and early mining and ranching, to help evaluate 

the best land use in the future. 

• Promote soil studies and surveys, especially 

concerning how soils relate to the landscape and land 

use. 
 NPS Geologic Resources Division 6 

Geologic Features and Processes 

This section describes the most prominent and distinctive geologic features and processes 

in Lyndon B. Johnson National Historical Park. 

Geology and History Connections 

One of the major goals of the park is to preserve the 

historical context of the area; this includes preserving 

and restoring old buildings and the landscape around 

them. Maintaining this landscape often means resisting 

natural geologic changes, thus presenting several 

management challenges. 

Slopes processes, such as landsliding, slumping, chemical 

weathering, block sliding, and slope creep, are constantly 

changing the landscape at the park. Runoff removes 

sediments exposed at the surface and carries them down 

streams and gullies. Erosion naturally diminishes higher 

areas and fills in the lower areas, distorting the historical 

context of the landscape. 

Issues also arise from opposing values in managing 

cultural and natural resource. For example, a proposal 

for restoration of a historic building may consist of 

removing surrounding natural resources or adding exotic 

plants. 

The park highlights the cattle ranching history in central 

Texas. This history extends beyond European settlement 

to the early fields, settlements, and 12,000- year- old tool 

quarries of the Native Americans. They left artifacts and 

changes in the landscape, such as campsites, tool 

quarries, and other archaeological sites in Texas Hill 

Country. 

The history of the area is heavily influenced by its 

geology. The gullies and ravines carved into the Edwards 

Plateau region made travel and farming difficult. Because 

of the local topography and hydrography of the 

Pedernales River, large 100- and 500- year floodplains 

cover much of the park today. The combination of 

climate and landform rendered this landscape rich in 

prairies and grasslands for cattle grazing. 

Several areas in the park, such as the Junction School, 

LBJ Birthplace, Sam Ealy Johnson Sr. Farmhouse, the 

Bailey House, and the Cedar Guest House lie within the 

100- year floodplain. The Texas White House (Ranch 

House) lies on the 500- year floodplain. Park historic 

structures require protection from geologic processes to 

coexist in harmony with the landscape (fig. 2A−D) and 

need to be available to visitors without compromising the 

natural resources or the historical context. E.C. Bearss 

wrote the Historic Structure Report: Texas White House, 

Lyndon B. Johnson National Historical Park, Texas, in 

1986 (published by Santa Fe, N.M.: Division of 

Conservation, Southwest Cultural Resources Center, 

NPS, U.S. DOI). This document could serve as an 

interpretive tool and guide for preservation of the 

historic structures. 

Llano Uplift 

The 1.5- billion- acre Llano Uplift—also known as the 

Central Mineral Region—of central Texas comprises 

igneous and metamorphic rocks as part of a long- lived 

collisional orogenic belt that formed during the 

Precambrian Grenville Orogeny (Kier 1988; Li et al. 2005; 

Mosher and Levine 2005). This belt formed along the 

southern margin of the Laurentian (proto- North 

American) continent. 

The uplift differs in structure, metamorphic grade, and 

rock assemblages between the eastern and western parts. 

The eastern part records the collision between a volcanic 

arc and the Laurentian continent, and the western part 

records continent- continent collision with one or more 

southern continental masses (possibly including the 

Amazon craton of South America) (Tohver et al. 2002; 

Rivers 2004; Mosher and Levine 2005). These 

deformational events took place intermittently over 200 

million years (Grimes and Copeland 2004; Rivers 2004). 

“Llano” translates to “plain” in Spanish, probably a 

corruption of the French name given to the local Lipan 

Indians. The term “uplift” is a bit of a misnomer since the 

area is not a topographic high. Instead, the term refers to 

the juxtaposition of Precambrian rocks uplifted relative 

to much younger Cretaceous limestone. The numerous 

fault blocks comprising the uplift are oriented southwest 

to northeast (Kier 1988). The relatively low- density 

granitic rocks of the locally thickened crust “float” on the 

denser rocks of the Earth’s mantle (Reed 2005). The 

crust thickened during the orogenic collision and 

associated plutonism of the Grenville event. 

According to the City of Llano, the Llano Uplift contains 

the only known specimens of the granite known as 

llanite. This brown granite contains visible crystals 

(phenocrysts) of sky- blue quartz and rusty- pink 

feldspar in a matrix of microscopic quartz, feldspar, 

biotite, and minor fluorite, magnetite, apatite, and zircon 

crystals. This unique rock typically occurs as dikes of 

≈1,093- Ma age (Reed 2005). It is treasured as a decorative 

polished stone. 

Gem quality topaz and some gold associated with 

pegmatite dikes are also present in the area. Gold is 

found either as native gold, or in association with sulfide 

minerals, such as pyrite, quartz veins, and quartz 

stringers, as well as residual soils and saprolite (Heylum 

1985). Some small- scale mines in the area surrounding 

the park are the Heath, Central Texas, and Los Almagres 

mines. Many others small mines explored by early 

Spanish settlers in the 1700s are known only through 

local legends of buried treasures (Heylum 1985). 
 LYJO Geologic Resource Evaluation Report 7

Geology and Biology Connections 

Geology forms the basis of the entire ecosystem at 

Lyndon B. Johnson National Historical Park. The 

relationships between geology and biology at the park 

are poorly understood, and yet the vast array of species 

correlates in part with the underlying geology. In recent 

animal surveys, 18 fish species, 17 amphibian species, 58 

reptile species, and 17 mammal species were positively 

identified in the park. Many species of birds migrate 

through the area (Patrikeev 2004). 

A total of 559 species of vascular plants (naturally 

occurring, hybrids, and cultivated) occur in the park. 

Park staff have identified nine major plant associations, 

defined on the basis of physiographic, geologic, and soil 

types: (1) native grassland on chalky slopes with clayloam and loam; (2) native grassland and savanna on level, 

deep clayey loam and clay- loam; (3) native grassland and 

savanna on upland sandy loam; (4) pastures and fields on 

upland, deep redland clay- loam or sandy loam soils; (5) 

pasture and savanna on alluvial sandy and silty loam 

soils; (6) upland successional woodland; (7) riparian 

woodland; (8) ponds, deep swales, and stream margins; 

and, (9) urbanized habitats (including agricultural 

plantings) (Sanders 2004). 

Bank erosion is a major factor leading to the introduction 

of heavy sediment loads to the riverine environment. 

Land use affects stream bank erosion rates. Cattle 

grazing reduces the amount of buffering and stabilizing 

vegetation in riparian zones along the rivers and streams. 

Fenced segments of rivers in grazed areas usually have 

better fish habitat (Nimick 1990). 
 NPS Geologic Resources Division 8 

Figure 2A. Historic homestead structure at Lyndon B. Johnson National Historical Park. Photograph is courtesy of the park 

(http://www.exploitz.com/national_park/lyndon_b_johnson_national_historical_park/). 

Figure 2B. Historic structure of the birthplace (reconstructed) at Lyndon B. Johnson National Historical Park. Photograph is courtesy 

of the park (http://www.exploitz.com/national_park/lyndon_b_johnson_national_historical_park/). 
 LYJO Geologic Resource Evaluation Report 9

Figure 2C. Historic barn structure at Lyndon B. Johnson National Historical Park. Photograph is courtesy of the park 

(http://www.exploitz.com/national_park/lyndon_b_johnson_national_historical_park/). 
 NPS Geologic Resources Division 10 

Figure 2D. Historic structure at Lyndon B. Johnson National Historical Park. Photograph is courtesy of the park 

(http://www.exploitz.com/national_park/lyndon_b_johnson_national_historical_park/). 
 LYJO Geologic Resource Evaluation Report 11

Map Unit Properties 

This section identifies characteristics of map units that appear on the Geologic Resource 

Evaluation digital geologic map of Lyndon B. Johnson National Historical Park. The 

accompanying table is highly generalized and is provided for background purposes only. 

Ground- disturbing activities should not be permitted or denied on the basis of 

information in this table. More detailed map unit descriptions can be found in the help 

files that accompany the digital geologic map or by contacting the National Park Service 

Geologic Resources Division. 

Locally the Llano Uplift consists of the Valley Spring 

Gneiss, Oatman Creek Granite, and Town Mountain 

Granite, all Precambrian. The granite in these units is 

fine- to medium- grained and porphyritic (Reed et al. 

1996). These units are cut by several northeast- to 

southwest- trending faults. The deformational structures 

of this uplift record the ancient Grenville orogenic event. 

Both the LBJ Ranch and Johnson City districts of the 

park are within the Pedernales River drainage basin. In 

the central part of this valley, the river flows across 

jointed Paleozoic dolomite and limestone of the San 

Saba, Point Peak, Morgan Creek Limestone, and Welge 

Sandstone members of the Wilberns Formation, and the 

Riley Formation, including the Lion Mountain 

Sandstone Member, the Cap Mountain Limestone 

Member, and the Hickory Sandstone Member. These 

Cambrian units record the transgressions and 

regressions of an ancient sea across the buried uplift. 

Continued marine deposition throughout the Paleozoic 

resulted in the dolomite, limestone, calcite, and chertrich units of the Ordovician Tanyard Formation 

(Staendeback and Threadgill Members), as well as the 

fossiliferous Gorman and Honeycut formations of the 

Ellenburger Group. 

These units support some cave development along joints 

and show karren and solution pockets (Fieseler 1978). 

The Devonian dolomite and limestone of the Stribling 

Formation are separated from underlying Ordovician 

units, overlying erosional surfaces in Mississippian and 

Pennsylvanian units. 

The Mississippian Houy and Barnett Formations, as well 

as the Chappel Limestone, are rich in fossil records and 

contain radioactive phosphatic layers. Pennsylvanian 

units include the Smithwick Formation, consisting of 

gray shale, and interbedded layers of shale, and massive 

limestone of the Marble Falls Limestone. A major 

unconformity separates Paleozoic limestone from the 

overlying Cretaceous sandstone, shale, and limestone in 

the map area. 

In the area surrounding the Lyndon B. Johnson 

Historical Park, the Cretaceous Hensell Sand and Glen 

Rose Limestone Members of the Shingle Hills Formation 

dominate the upland rock units. Elsewhere within the 

map area, in the lower parts of the Pedernales River 

valley, the area is underlain by Cretaceous units, 

including the Travis Peak Formation, which comprises 

the Cow Creek Limestone, Hammett Shale and 

Sycamore Sand Members. 

Surficial deposits of Quaternary- Pleistocene alluvium, 

floodplain alluvium, colluvium, and terrace deposits 

cover most of the bedrock in the area of the park. These 

deposits include well- sorted to poorly sorted gravel, 

sand, silt, and clay. Travertine deposits are associated 

with springs in the area. Travertine typically forms 

calcium carbonate cement between alluvial grains. 

The following pages are a table that combines a 

stratigraphic column (the map units in order of 

occurrence with depth) and a list of features in each 

stratigraphic unit: description, resistance to erosion, 

suitability for development, hazards, potential 

paleontologic resources, cultural and mineral resources, 

potential karst issues, recreational use potential, and 

global significance. 

 LYJO Geologic Resource Evaluation Report 15

Geologic History 

This section describes the rocks and unconsolidated deposits that appear on the digital 

geologic map of Lyndon B. Johnson National Historical Park, the environment in which 

those units were deposited, and the timing of geologic events that created the present 

landscape. 

The geologic story of Lyndon B. Johnson National 

Historical Park begins in the Proterozoic Eon (fig. 3). 

Little is known about this period of Earth’s history. Most 

rocks on Earth of Precambrian age are highly deformed 

and metamorphosed, losing most, if not all, traces of 

their original structures. Metamorphic rocks record— 

with textures and mineral assemblages— the conditions 

during deformational events. The oldest rocks in central 

Texas preserve a vast geologic history. 

The Llano Uplift records the Grenville orogenic event of 

the Proterozoic Eon (Mosher and Levine 2005). This 

event involved much of the continental crust in existence 

at that time. A northern landmass, Laurentia (presentday North America), collided with one or more southern 

landmasses and island arcs (Mosher et al. 2004). 

These intermittent collisions caused the uplift of a long, 

east- trending mountain range and the intrusion of 

several igneous plutons over a long time period 

(≈1165−1068 Ma) (Li and Barnes 2005; Reed and Rougvie 

2002). Many valuable mineral deposits in central Texas 

are associated with the high pressure and high 

temperature that accompanied deformation of these 

rocks (Hentz 2001). 

Grenville- age structures are found in northeastern 

Canada, in patches along the length of the Appalachians, 

and through central and western Texas. The Carrizo 

Mountain Group, some 500 km (310 mi) to the west of 

the Llano Uplift, continues the Grenville trend (Grimes 

and Copeland, 2004). Corresponding deformational 

structures and rock assemblages occur in the western 

Amazon craton, possibly marking the South American 

continent as the southern landmass involved in the 

Grenville orogeny (Tohver et al. 2002). 

Following this uplift, erosion beveled the highlands and 

vast quantities of sediments were deposited into an 

emergent sedimentary basin during Cambrian rift events. 

The so- called Ouachita rift (or trough) extends 

southward from the Alabama- Oklahoma transform fault 

to Mexico, defining the Ouachita embayment in the 

Precambrian crust (fig. 4) (Thomas and Keller 1999). 

Carbonate beds formed during periods of marine 

highstands, dominating the rock record in the basin to 

the southeast, as well as in several small- scale failed rift 

areas farther inland (Harrison 1997; Hentz 2001). When 

regional sea level dropped, sediments that became shale 

and intercalated sandstone were deposited across the 

basin (Harrison, 1997). 

Deposition in shallow seas continued in central Texas 

throughout the early to middle Paleozoic (Cambrian, 

Ordovician, Silurian, and Devonian), leaving vast a 

sediment package grading from coarse sandstone and 

conglomerate in the near- shore areas to chert, 

limestone, and dolomite in the deeper areas to the south 

and east. Abundant fossils in the Paleozoic units reveal 

the extent of ancient life in this shallow- sea environment 

(Pierson 2005). 

Orogenic activity began again during MississippianPennsylvanian time when the supercontinent Pangaea 

formed through the collision between North America 

and the other continental landmasses (European and 

African−South American plates). This resulted in the 

formation of the Ouachita Mountains in central Texas, 

northwest Arkansas, and southeast Oklahoma (Hentz 

2001; Pierson 2005). 

Many north- to northeast- trending strike- slip and 

thrust faults were active, responding to multi- directional 

tectonic stresses at this time (Amsbury and Haenggi 

1993). Regionally, this event is referred to as the Ouachita 

orogeny. The early Paleozoic sediments deposited in the 

Ouachita trough were buckled and thrust up into 

mountainous highlands. Locally, the sedimentary rocks 

were more mildly deformed (Torrez 1996). 

As the Ouachita Mountains rose in central Texas, many 

basins to the north and west formed along a foreland 

basin, including the Midland and Delaware basins 

(Hentz 2001). This type of basin forms in response to the 

force of increasing mass on the crust during mountain 

building. In effect, the earth’s crust warps beneath the 

mountain mass, creating a basin that fills with sediments 

eroded from the nearby highlands. The basin sinks 

further as more sediments pour in adding a heaver load. 

Deposition of fine sediments in the brackish foreland 

basins (West Texas Basin) continued throughout the 

Permian. Erosion beveled the Ouachita Mountains to the 

east. Broad carbonate shelves and reefs surrounded the 

deeper parts of the basins. Rivers flowed from the 

highlands into the basins, forming deltas. 

Associated coastlines shifted repeatedly as near- shore 

sediments were continuously deposited and eroded by 

shoreline processes (Bureau of Economic Geology 1992). 

These shallow seas and shorelines supported vast 

quantities of organic material that interlayered with 

porous sediments. These deposits are a major 

contributor to the hydrocarbon resources in Texas 
 NPS Geologic Resources Division 16 

(Pierson 2005). During the late Permian, near the end of 

the Paleozoic Era, the inland seas retreated 

southwestward as the climate became hot and dry and 

broad evaporite basins developed in West Texas. Vast 

red mud, salt, and gypsum deposits in West Texas record 

this change (Bureau of Economic Geology 1992). 

The Cambrian rift feature was reactivated during an early 

Mesozoic extensional event (≈220−245 Ma) that resulted 

in the opening of the Gulf of Mexico (Bureau of 

Economic Geology 1992; Thomas and Keller 1999). The 

continents pulled apart during the Triassic and Jurassic 

Periods, creating large basins to hold sediments shed 

from the rapidly eroding Ouachita highlands. In the early 

stages, a series of discontinuous rift basins developed 

parallel to the edge of the opening ocean basin. These 

basins extended from Mexico to Nova Scotia (Hentz 

2001). 

As rifting continued, thick deposits of Middle Jurassic 

salt buried the earlier rift basins in Texas. This 

accompanied the development of the East Texas and 

Gulf Coast basins (Hentz 2001). As the basins widened, 

areas in the south and east of Texas warped downwards 

and continued to subside under the weight of added 

sediments. Sediments were deposited over the marine 

salt and limestone shelves from earlier basins (fig. 5). This 

juxtaposition of rock types led to the formation of many 

hydrocarbon traps and folds in the East Texas basin 

(Bureau of Economic Geology 1992). Much of the 

Coastal Plain of Texas was formed during the heavy 

sedimentation of this time (Hentz 2001). 

Continued erosion and burial throughout the Cretaceous 

beveled the Ouachita Mountains nearly flat (Pierson 

2005). As the Rocky Mountains formed, orogenic events 

in the western United States provided more sediment to 

a pervasive seaway present intermittently throughout the 

Cretaceous. Most of Texas was covered by this inland 

sea. By Late Cretaceous the seaway deepened, resulting 

in deposition of carbonate sediments mixed with deltaic 

and strandline sand, forming the reservoir rocks for the 

productive East Texas oilfields (Hentz 2001). Some 

widespread Late Cretaceous volcanic activity in 

southeastern Texas trended parallel to the buried 

Ouachita Mountains. 

The Cretaceous Period ended with the mass extinction 

of numerous plant and animal species. When the 

Cenozoic Era began (≈66 Ma), the East Texas basin was 

filling with fluvial- deltaic sediments, including plant 

remains that later formed lignite. As mountains were 

rising to the west during the Laramide Orogeny, the seas 

retreated off the continent. The early Mississippi River 

flowed across East Texas, ending at a large delta north of 

the current shoreline near Houston. The Tertiary Period 

is marked by deposition of massive fluvial- deltaic 

sediments eroded from the young Rocky Mountains and 

transported southeastward into the widening Gulf of 

Mexico (Bureau of Economic Geology 1992; Hentz 2001). 

Following orogenic activity in the west, a period of 

extensional tectonic and igneous activity during the 

middle Tertiary Period resulted in pervasive faulting and 

volcanism (fig. 6). In the western part of Texas, volcanic 

activity (≈47−17 Ma), produced about 14 volcanic centers 

as well as thick lava- flow and ash- fall deposits. The 

extensional tectonic regime that typically produces 

basin- and- range topography began about 30 Ma in 

Texas (Hentz 2001). 

In the middle Tertiary Period (Miocene Epoch), regional 

uplift of the Edwards Plateau resulted in rapid erosion 

into the stair step topography found today in the area 

surrounding Lyndon B. Johnson National Historical 

Park (Pierson 2005). Alluvial and windblown material 

from the Rocky Mountains were deposited in thick 

sheets and fans across the central and southern High 

Plains (Hentz 2001). These units bear major aquifers that 

have sustained agriculture in a typically dry climate. 

Pleistocene glaciation never reached central Texas; 

however, the effects left a record on the landscape. The 

cooler climate resulted in changes to regional flora and 

fauna. Wooly mammoth, camel, and bison fossils of 

central Texas attest to some of these changes. Deciduous 

forests extended southward (Pierson 2005). Local sea 

level dropped 90−120 m (300−400 ft) during glacial 

maxima (Hentz 2001). Windblown dust (loess) evolved 

into fertile soils for prairies and grasslands. Glacial 

meltwater scoured and entrenched major watersheds, 

such as the Colorado, Canadian, Trinity, and Brazos 

(Pierson 2005). 
 LYJO Geologic Resource Evaluation Report 17

Figure 3. Geologic time scale; adapted from the U.S. Geological Survey (http://pubs.usgs.gov/fs/2007/3015/). Red lines indicate major 

unconformities between eras. Included are major events in life history and tectonic events occurring on the North American continent. 

Absolute ages shown are in millions of years. 
 NPS Geologic Resources Division 18 

Figure 4. Map showing Ouachita tectonic front southeast of Lyndon B. Johnson National Historical Park (approximate location noted as 

green circle) near the Llano Uplift (purple area). Crosscutting faults of the Llano Uplift area are also noted as heavy black lines. Graphic 

created by Trista L. Thornberry-Ehrlich (Colorado State University) from information from the University of Texas at Austin 

(http://www.lib.utexas.edu/geo/). 
 LYJO Geologic Resource Evaluation Report 19

Figure 5. Diagram showing the evolution of the Ouachita highland during Mesozoic rifting resulting in the opening of the Gulf of Mexico. 

Graphic created by Trista L. Thornberry-Ehrlich (Colorado State University). 
 NPS Geologic Resources Division 20 

Figure 6. Map showing structural features in the area of Lyndon B. Johnson National Historical Park (approximate location noted as green 

circle) near the Llano Uplift. Graphic created by Trista L. Thornberry-Ehrlich (Colorado State University) from information from the University 

of Texas at Austin http://www.lib.utexas.edu/geo/ 
 LYJO Geologic Resource Evaluation Report 21

Glossary 

This glossary contains brief definitions of technical geologic terms used in this report. Not all 

geologic terms used are referenced. For more detailed definitions or to find terms not listed 

here please visit: http://wrgis.wr.usgs.gov/docs/parks/misc/glossarya.html. 

alluvium. Stream- deposited sediment that is generally 

rounded, sorted, and stratified. 

aquifer. Rock or sediment that is sufficiently porous, 

permeable, and saturated to be useful as a source of 

water. 

ash (volcanic). Fine pyroclastic material ejected from a 

volcano (also see “tuff”). 

asthenosphere. Weak layer in the upper mantle below 

the lithosphere where seismic waves are attenuated. 

basin (structural). A doubly- plunging syncline in which 

rocks dip inward from all sides (also see “dome”). 

basin (sedimentary). Any depression, from continental 

to local scales, into which sediments are deposited. 

bed. The smallest sedimentary strata unit, commonly 

ranging in thickness from 1 cm (2.5 in.) to 1−2 m (3−6 ft) 

and distinguishable from beds above. 

chemical weathering. The dissolution or chemical 

breakdown of minerals at the Earth’s surface via 

reaction with water, air, or dissolved substances. 

clastic. Rock or sediment made of fragments of preexisting rocks. 

clay. Clay minerals or sedimentary fragments the size of 

clay minerals (>1/256 mm). 

continental crust. The type of crustal rocks underlying 

the continents and continental shelves; having a 

thickness of 25−60 km (16−37 mi) and a density of 

approximately 2.7 grams per cubic centimeter. 

cross section. A graphical interpretation of geology, 

structure, and/or stratigraphy in the third (vertical) 

dimension based on mapped and measured geological 

extents and attitudes depicted in an oriented vertical 

plane. 

crust. The outermost compositional shell of the Earth, 

10−40 km (6−25 mi) thick, consisting predominantly of 

relatively low density silicate minerals. 

crystalline. Describes the structure of a regular, orderly, 

repeating geometric arrangement of atoms; also often 

used to mean igneous and metamorphic rock. 

deformation. A general term for the process of faulting, 

folding, shearing, extension, or compression of rocks 

as a result of various forces in the Earth. 

drainage basin. The total area from which a stream 

system receives or drains runoff. 

evaporite. Chemically precipitated mineral(s) formed by 

the evaporation of solute- rich water under restricted 

conditions. 

fault. A subplanar break in rock along which one side 

moves relative to the other. 

formation. Fundamental rock- stratigraphic unit that is 

mappable and lithologically distinct from adjoining 

strata and has definable upper and lower contacts. 

glauconitic. Containing the greenish clay mineral 

glauconite, often associated with marine sediments. 

igneous. Refers to a rock or mineral that originated from 

molten material; one of the three main classes of rocks: 

igneous, metamorphic, and sedimentary. 

intrusion. A body of igneous rock that invades older, 

solid rock. The invading rock may be a plastic solid or 

molten matter that pushes its way into the solid rock. 

island arc. A line or arc of volcanic islands formed over 

and parallel to a subduction zone. 

landslide. Any process or landform resulting from rapid 

mass movement under relatively dry conditions (cf.: 

debris flow). 

magma. Molten rock generated within the Earth that is 

the parent of igneous rocks. 

matrix. The fine- grained interstitial material between 

coarse grains in porphyritic igneous rocks and poorly 

sorted clastic sediments or rocks. 

member. A lithostratigraphic unit with definable contacts 

that is a subdivision of a formation. 

metamorphic. Pertaining to the process of 

metamorphism or to its results. 

metamorphism. Literally, “change in form.” 

Metamorphism occurs in rocks with mineral 

alteration, genesis, and/or recrystallization from 

increased heat and pressure. 

orogeny. A mountain- building event, particularly a 

well- recognized event in the geological past (e.g., the 

Laramide orogeny). 

plateau. A broad, flat- topped topographic high of great 

extent and elevation above the surrounding plains, 

canyons, or valleys (both land and marine landforms). 

point bar. A sand and gravel ridge deposited in a stream 

channel on the inside of a meander where flow 

velocity slows. 

recharge. Infiltration processes that replenish 

groundwater. 

regression. A long- term seaward retreat of the shoreline 

or relative fall of sea level. 

sandstone. Clastic sedimentary rock of predominantly 

sand- size grains. 

sediment. An eroded and deposited, unconsolidated 

accumulation of lithic and mineral fragments. 

sedimentary rock. A consolidated and lithified rock 

consisting of detrital and/or chemical sediment(s). 
 NPS Geologic Resources Division 22 

silt. Clastic sedimentary material intermediate in size 

between fine- grained sand and coarse clay (1/256−1/16 

mm). 

strata. Tabular or sheet like masses or distinct layers 

(e.g., of rock). 

strike. The compass direction of the line of intersection 

that an inclined surface makes with a horizontal plane. 

stromatolite. An organic sedimentary structure formed 

by blue- green algae (cyanophytes). 

stylolite. A seam (contact or surface) of insoluble 

constituents (e.g. clay, carbon, iron oxides) usually 

found in carbonate rocks.

tectonic. Relating to large- scale movement and 

deformation of the Earth’s crust. 

terraces (stream). Step- like benches surrounding the 

present floodplain of a stream due to dissection of 

previous flood plain(s), stream bed(s), and/or valley 

floor(s). 

thrust fault. A contractional, dip- slip fault with a 

shallow- dipping fault surface (<45o

) where the 

hanging wall moves up and over relative to the 

footwall. 

transgression. Landward migration of the sea due to a 

relative rise in sea level. 

travertine. A limestone deposit or crust, commonly 

banded, formed from precipitation of calcium 

carbonate from saturated waters, especially near hot 

springs and in caves. 

trend. The direction or azimuth of elongation or a linear 

geological feature. 

unconformity. A surface within sedimentary strata that 

marks a prolonged period of nondeposition or 

erosion. 

uplift. A structurally high area in the crust, produced by 

movement that raises the rocks. 

volcanic. Related to volcanoes; describes igneous rock 

crystallized at or near Earth’s surface (e.g., lava).
 LYJO Geologic Resource Evaluation Report 23

References 

This section lists references cited in this report as well as a general bibliography that may 

be of use to resource managers. A more complete geologic bibliography is available from 

the National Park Service Geologic Resources Division. 

Amsbury, D. L., and W. T. Haenggi. 1993. Middle 

Pennsylvanian strike- slip faulting in the Llano Uplift, 

central Texas. Bulletin of the South Texas Geological 

Society 34 (1): 9−16. 

Anderson, A.L., Miller, C.V., Olsen, L.D., Doheny, E.J., 

Phelan, D.J., 2002, Water quality, sediment quality, and 

stream- channel classification of Rock Creek, 

Washington, D.C., 1999- 2000, Water- Resources 

Investigations - U. S. Geological Survey, 91 p. 

Barnes, V. E. 1963. Geology of the Johnson City 

Quadrangle, Blanco County, Texas. Scale 1:24,000. 

Geologic Quadrangle Map 25. University of Texas at 

Austin, Bureau of Economic Geology. 

Barnes, V.E. 1965a. Geology of the Hye Quadrangle, 

Blanco, Gillespie, and Kendall Counties, Texas. Scale 

1:24,000. Geologic Quadrangle Map 27. University of 

Texas at Austin, Bureau of Economic Geology. 

Barnes, V. E. 1965b. Geology of the Rocky Creek 

Quadrangle, Blanco and Gillespie Counties, Texas. Scale 

1:24,000. Geologic Quadrangle Map 29. University of 

Texas at Austin, Bureau of Economic Geology. 

Barnes, V. E. 1966. Geology of the Stonewall Quadrangle, 

Gillespie, and Kendall Counties, Texas. Scale 1:24,000. 

Geologic Quadrangle Map 31. University of Texas at 

Austin, Bureau of Economic Geology. 

Barnes, V. E. 1967a. Geology of the Cave Creek School 

Quadrangle, Gillespie County, Texas. Geologic 

Quadrangle Map, no. 32 (scale 1:24,000). University of 

Texas at Austin, Bureau of Economic Geology. 

Barnes, V. E. 1967b. Geology of the Monument Hill 

Quadrangle, Blanco County, Texas. Scale 1:24,000. 

Geologic Quadrangle Map 33. University of Texas at 

Austin, Bureau of Economic Geology. 

Barnes, V. E. 1967c. Geology of the Yeager Creek 

Quadrangle, Blanco and Hays Counties, Texas. Scale 

1:24,000. Geologic Quadrangle Map 34. University of 

Texas at Austin, Bureau of Economic Geology. 

Barnes, V. E. 1982. Geology of the Pedernales Falls 

Quadrangle, Blanco County, Texas. Scale 1:24,000. 

Geologic Quadrangle Map 49. University of Texas at 

Austin, Bureau of Economic Geology. 

Bickford, M. E., K. Soegaard, K. C. Nielsen, and J. M. 

McLelland. 2000. Geology and geochronology of 

Grenville- age rocks in the Van Horn and Franklin 

Mountains area, West Texas: Implications for the 

tectonic evolution of Laurentia during the Grenville. 

Geological Society of America Bulletin 112 (7): 1134−1148. 

Breuninger, A.B., 2000, Effects of floodplain remediation 

on bed sediment contamination in the Upper Clark 

Fork River basin, western Montana. University of 

Montana, Master’s thesis, 182 p. 

Brown, J. B. 1980. Mesozoic history of the Llano region, 

Texas. In Geology of the Llano region, central Texas, ed. 

D. Windle, 52−58. 80- 73, TX: West Texas Geological 

Society. 

Bureau of Economic Geology. 1992. Geology of Texas. 

Four map sheets, scale 1:500,000. University of Texas 

at Austin, Bureau of Economic Geology. 

Button, R. M. 1980. Economic geology of the Llano 

region. In Geology of the Llano region, central Texas, ed. 

D. Windle, 76−82. 80- 73, TX: West Texas Geological 

Society. 

Denney, J. H. Jr. and V. W. Goebel. 1984. Complexity of 

regional deformation of Precambrian rocks, 

northeastern Llano Uplift, central Texas. Abstracts 

with Programs, 82, vol. 16, no. 2. Boulder, CO: 

Geological Society of America. 

Fieseler, R. G. 1978. Cave and karst distribution of Texas. 

In An introduction to the caves of Texas, ed. R. G. 

Fieseler, J. Jasek, and M. Jasek, 15−53. Annual 

Convention Guidebook, National Speleological 

Society: 19. 

Grimes, S.W. and P. Copeland. 2004. Thermochronology 

of the Grenville Orogeny in West Texas. Precambrian 

Research 131 (1- 2): 23−54. 

Harrison, E. 1997. Sequence stratigraphy of the Concho 

Platform, north- central Texas. AAPG Bulletin 81 (5): 

867. 

Hentz, T.F. 2001. Geology. In The handbook of Texas. 

University of Texas at Austin, 

http://www.tsha.utexas.edu/ 

handbook/online/articles/GG/swgqz.html. 
 NPS Geologic Resources Division 24 

Heylmun, E. B. 1985. Gold in central Texas. California 

Mining Journal 54 (12): 12−14. 

Johnson, B. 1983. Anatomy of a normal fault in the Llano 

Uplift. Abstracts with Programs, 38−39, vol. 15, no. 1. 

Boulder, CO: Geological Society of America. 

Johnson, B. 1990. The Llano Uplift: A plate flexural 

model and its associated implications. Abstracts with 

Programs, 9−10, vol. 22, no. 1. Boulder, CO: Geological 

Society of America. 

Kier, R. S. 1988. Paleozoic strata of the Llano region, 

central Texas. In Collection centennial field guide, 351-

360. Annual Meeting Guidebook, South- Central 

Section of the Geological Society of America: 4. 

Li, Y., M. A. Barnes, and C. G. Barnes. 2005. Widespread 

Grenville- age magmatism in the basement of West 

Texas and adjacent New Mexico. Abstracts with 

Programs, 38, vol. 37, no. 3. Boulder, CO: Geological 

Society of America. 

McGookey, D. P. 2004. Geologic wonders of West Texas : 

Midland, TX: Donald P. McGookey. 

Miller, A.J., J.A. Smith, and L.L. Shoemaker, L.L. 1984. 

Channel storage of fine- grained sediment in the 

Monocacy River basin. Eos, Transactions, American 

Geophysical Union 65 (45): 888 

Mosher, S. ed. 1996. Guide to the Precambrian geology of 

the eastern Llano Uplift, central Texas. Fieldtrip Guide 

for the Geological Society of America, 30th Annual 

Meeting. Austin, TX: South- Central Section of the 

Geological Society of America. 

Mosher, S. 1999. The Texas Grenville Orogen. Abstracts 

with Programs, 31, vol. 31, no. 1. Boulder, CO: 

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Zumbro. 2001. Mesoproterozoic tectonic evolution of 

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central Texas: A record of Grenville orogenesis along 

the southern Laurentian margin. In Proterozoic tectonic 

evolution of the Grenville Orogen in North America, ed. 

R. P. Tollo, L. Corriveau, J. McLelland, and M. J. 

Bartholomew, 783−798. Memoir 197. Boulder, CO: 

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along the southern Laurentian margin: Contrasts 

between the eastern and western Llano Uplift, central 

Texas. Abstracts with Programs, 7, vol. 34, no. 3. 

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Grenville- aged orogenic belt; Llano Uplift, central 

Texas. Abstracts with Programs, 14, vol. 37, no. 3. 

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Nimick, D.A., 1990, Stratigraphy and chemistry of metalcontaminated floodplain sediments, upper Clark Fork 

River valley, Montana. University of Montana, 

Master’s thesis, 118 p. 

Nordt, L. 2003. Late Quaternary geology and 

geoarchaeology of the LBJ Ranch District and Johnson 

City District in Gillespie and Blanco Counties, Texas. 

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#Q750030001. 

Patrikeev, M. 2004. Fish, amphibians, reptiles, and 

mammals of Lyndon B. Johnson National Historical 

Park, Gillespie and Blanco Counties, Texas. Report 

prepared by the Texas Conservation Data Center—

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Service. 

Pierson, D. G. 2005. Geology of North Central Texas. In 

A Natural History of North Central Texas,

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Reed, R. M. 2005. Rob’s granite page. 

http://uts.cc.utexas.edu/ 

~rmr/index.html. 

Reed, R. M., R.A. Eustice, J. R. Rougvie, and J.F. Reese. 

1996. Sedimentary structures, paleo- weathering, and 

protoliths of metamorphic rocks, Grenvillian Llano 

Uplift, central Texas. Abstracts with Programs, 59, vol. 

28, no. 1. Boulder, CO: Geological Society of America. 

Reed, R. M., and J.R. Rougvie. 1998. Late syn- orogenic to 

post- orogenic granites in the Grenvillian Llano Uplift, 

central Texas. Joint Annual Meeting Program with 

Abstracts, Geological Association of Canada, 

Mineralogical Association of Canada, and Canadian 

Geophysical Union: 153−154, vol. 23. 

Reed, R. M., and J.R. Rougvie. 2002. Low- pressure 

deformation and metamorphism of the Proterozoic 

Llano Uplift, central Texas. Abstracts with Programs, 

7, vol. 34, no. 3. Boulder, CO: Geological Society of 

America. 

Reese, J. F. 1993. The tectonic evolution of the 

southeastern Llano Uplift, central Texas: A summary 

of recent results from structural and U- Pb 

geochronologic studies. Abstracts with Programs, 

297−298, vol. 25, no. 6. Boulder, CO: Geological 

Society of America. 

Reese, J. F. 1995. Structural evolution and geochronology 

of the southeastern Llano Uplift, central Texas. PhD 

diss., University of Texas at Austin. 
 LYJO Geologic Resource Evaluation Report 25

Rivers, T., 2004, Architecture and tectonic evolution of 

the Grenville Province: Part of a hot wide orogen that 

developed over 200 my on the southeastern margin of 

Laurentia. http://www.lithoprobe.ca/ 

Contributed%20Abstracts/Oral%20Presentation/Rive

rs_LithoprobeAbstract_TO_04.pdf. 

Sanders, R. W. 2004. Vascular plants of Lyndon B. 

Johnson National Historical Park, Blanco and 

Gillespie Counties, Texas. Report prepared by the 

Texas Conservation Data Center—The Nature 

Conservancy for the National Park Service. 

Snyder, M. 1980. A brief human history of the Llano 

region. In Geology of the Llano region, central Texas, ed. 

D. Windle, 108−113. 80- 73, TX: West Texas Geological 

Society. 

Thomas, W. A., and G. R. Keller. 1999. Cambrian rifting 

and subsequent structures in eastern Texas. Annual 

Meeting Expanded Abstracts, American Association of 

Petroleum Geologists A138. 

Tohver, E., B. A. van der Pluijm, R. Van der Voo, G. 

Rizzotto, and J. E. Scandolara. 2002. Paleogeography 

of the Amazon Craton at 1.2 Ga: Early Grenvillian 

collision with the Llano segment of Laurentia. Earth 

and Planetary Science Letters 199 (1- 2): 185−200. 

Torrez, B. D. 1996. Intragranular strains in Paleozoic 

limestones of the Llano Uplift: Implications for the 

direction of convergence along the OuachitaMarathon orogen in east- central Texas. Abstracts 

with Programs, 66, vol. 28, no. 1. Boulder, CO: 

Geological Society of America. 

Watson, W.G. 1980. Paleozoic stratigraphy of the Llano 

Uplift area:A review. In Geology of the Llano region, 

central Texas, ed. D. Windle, 28- 51. 80- 73, TX: West 

Texas Geological Society. 

Wilson, M. H. 1994. A geologic field guide to the Llano 

Uplift and surrounding area. Master’s thesis, Baylor 

University. 
 NPS Geologic Resources Division 26 

Appendix A: Geologic Map Graphic 

The following page is a preview or snapshot of the geologic map for Lyndon B. Johnson 

National Historical Park. For a poster- size PDF of this map or for digital geologic map 

data, please see the included CD or visit the Geologic Resource Evaluation publications 

Web page (http://www2.nature.nps.gov/geology/inventory/gre_publications). 
 LYJO Geologic Resource Evaluation Report 29

Appendix B: Scoping Agenda and Notes 

The following excerpts are from the GRE scoping summary for Lyndon B. Johnson 

National Historical Park. The scoping meeting was on May 15, 2003; therefore, the 

contact information and Web addresses referred to in this appendix may be outdated. 

Please contact the Geologic Resources Division for current information. 

Executive Summary 

A Geologic Resource Evaluation workshop was held for 

Lyndon B. Johnson National Historical Park (LYJO) on 

May 15, 2003 to view and discuss the park’s geologic 

resources, to address the status of geologic mapping for 

compiling both paper and digital maps, and to assess 

resource management issues and needs. Cooperators 

from the NPS Geologic Resources Division (GRD), NPS 

Lyndon B. Johnson NHP, Baylor University, and the 

Texas Bureau of Economic Geology were present for the 

workshop. This meeting was primarily set up to discuss 

proposed new soil maps through NCRS and a contracted 

geomorphic map prepared by Dr. Lee Cordt at Baylor 

University. 

This involved a field trip to view the geology of the 

Lyndon B. Johnson NHP area and a scoping session to 

present overviews of the NPS Inventory and Monitoring 

(I&M) program, the Geologic Resources Division, and 

the on- going Geologic Resource Evaluation (GRE). 

Round table discussions involving geologic issues for 

Lyndon B. Johnson NHP included interpretation, the 

status of geologic mapping efforts, sources of available 

data, and action items generated from this meeting. 

Overview of Geologic Resource Evaluation 

The NPS GRE has the following goals: 

• to assemble a bibliography of associated geological 

resources for NPS units with significant natural 

resources (“GRBIB”) to compile and evaluate a list of 

existing geologic maps for each unit, 

• to conduct a scoping session for each park, 

• to develop digital geologic map products, and 

• to complete a geological report that synthesizes much 

of the existing geologic knowledge about each park. 

It is stressed that the emphasis of the inventory is not to 

routinely initiate new geologic mapping projects, but to 

aggregate existing "baseline" information and identify 

where serious geologic data needs and issues exist in the 

National Park System. In cases where map coverage is 

nearly complete (ex. 4 of 5 quadrangles for Park “X”) or 

maps simply do not exist, then funding may be available 

for geologic mapping. 

After introductions by the participants, Anne Poole and 

Bruce Heise (both NPS- GRD) presented overviews of 

the Geologic Resources Division, the NPS I&M 

Program, the status of the natural resource inventories, 

and the GRE in particular. 

They also presented a demonstration of some of the 

main features of the GRE digital geologic database. This 

has become the prototype for the NPS digital geologic 

map model as it reproduces all aspects of a paper map 

(i.e. it incorporates the map notes, cross sections, legend 

etc.) with the added benefit of being geospatially 

referenced. It is displayed in ESRI ArcView shape files 

and features a built- in Microsoft Windows help file 

system to identify the map units. It can also display 

scanned JPG or GIF images of the geologic cross sections 

supplied with the paper "analog" map. Geologic cross 

section lines (ex. A- A') are subsequently digitized as a 

line coverage and are hyperlinks to the scanned images. 

Anne further demonstrated the developing NPS Theme 

Manager for adding GIS coverage’s into projects "onthe- fly". With this functional browser, numerous NPS 

themes can be added to an ArcView project with relative 

ease. Such themes might include geology, paleontology, 

hypsography (topographic contours), vegetation, soils, 

etc. 

GRBib 

At the scoping session, individual Microsoft Word 

Documents of Geologic Bibliographies for LYJO were 

distributed. 

The sources for this compiled information are as follows: 

• AGI (American Geological Institute) GeoRef 

• USGS GeoIndex 

• ProCite information taken from specific park libraries 

These bibliographic compilations were validated by GRE 

staff to eliminate duplicate citations and typographical 

errors, as well as to check for applicability to the specific 

park. After validation, they become part of a Microsoft 

Access database parsed into columns based on park, 

author, year of publication, title, publisher, publication 

number, and a miscellaneous column for notes. 

From the Access database, they are exported as 

Microsoft Word Documents for easier readability, and 

eventually turned into PDF documents. They are then 

posted to the GRE website at: for general viewing. 

Geologic Mapping 

Existing Geologic Maps and Publications 

After the bibliographies were assembled, a separate 

search was made for any existing surficial and bedrock 

geologic maps for LYJO. 
 NPS Geologic Resources Division 30 

The bounding coordinates for each map were noted and 

entered into a GIS to assemble an index geologic map. 

Separate coverage’s were developed based on scales 

(1:24,000, 1:100,000, etc.) available for the specific park. 

Numerous geologic maps at varying scales and vintages 

cover the area. Index maps were distributed to each 

workshop participant during the scoping session. 

There are nine quadrangles of interest: 

Fredericksburg West, Fredericksburg East, Cave Creek 

School, Rocky Creek, Johnson City, Oak Crest Park, 

Cain City, Stonewall, and Hye. 

Five of these quads, Cave Creek School, Rocky Creek, 

Johnson, Stonewall, and Hye exist as 1:24,000 geologic 

quadrangles mapped by Virgil Barnes. The Texas Bureau 

of Economic Geology participants indicated that these 

maps, while old, are scientifically sound and would 

require only edge matching and an updated stratigraphic 

name and/or geologic unit names to reconcile with later 

mapping work done south of the park. All of the maps 

are bedrock maps produced by TBEG as part of a Texas 

transportation corridor study. Also available are three 

quads to the east; Pedernales Falls, Monument, and 

Yeager Creek. None of these, however, were considered 

quads of interest by the park. None of these maps exist in 

digital format, and some are on a planimetric base that 

will need to be registered or rubber- sheeted. 

The park decided that the four quads of interest to the 

west; Fredericksburg West, Fredericksburg East, Oak 

Crest Park, and Cain City were not needed for their 

resource management. 

The final decision on which maps to provide as part of 

the Inventory: the GRE would digitize the Cave Creek 

School, Rocky Creek, Johnson, Stonewall, and Hye 

quadrangles internally. The GRE would provide 1⁄2 pay 

period to TBEG’s Eddie Collins to revamp the 

stratigraphic nomenclature (language in Task Order: 

Lyndon B. Johnson National Historic Park: 

The NPS will develop a digital geologic map of the LBJ 

National Historic Park based on 4 quadrangle maps 

published by the Bureau of Economic Geology in 1952 

(1:31,680, planimetric base) and 5 quadrangles published 

between 1963 and 1966 (1:24,000, topographic base) 

based on field mapping by Dr. Virgil Barnes between 

1939 and 1948. Stratigraphic nomenclature and 

subdivisions of many of the units have changed 

significantly since the original mapping, and these need 

to be updated to modern usage. Using the funding 

($2,500) provided by this contract, the Bureau will 

provide an updated composite stratigraphic column 

correlated to the map units so that the NPS digital map 

will include the currently accepted stratigraphic 

nomenclature and subdivisions. Bureau staff will be 

available to answer questions or provide guidance to 

NPS.) 

TBEG completed their revision and provided it to the 

GRD in 2004, to date it has not been incorporated into 

the help files of the completed geologic map. 

Other Topics of Discussion 

Dr. Lee Nordt, from Baylor University, has been 

contracted by the park to produce a geomorphic map of 

the park to be used for an archeological study. Nine 

trenches, produced by using a backhoe (significant 

excavations) will be dug as part of the geomorphic map. 

The map would also show the relationship and relative 

ages of the stream terraces that in turn could be used to 

predict higher potential for archeological sites. The park 

is particularly interested in 12,000- year bp lithic 

fragments that would possibly indicate a quarry site. 

Near Fredericksburg to the west, there is a nine meter 

thick alluvial terrace that might be cored as part of this 

same study. The park also hopes the geomorphology 

map would give an indication of the alluvial fill to 

bedrock along the Pedernales Creek bottom. The park 

was also very interested in a soil survey. Pete Biggam was 

originally scheduled to participate but was unable to, so 

the soil map discussion was incidental. 

Essentially, the park wants to tie the soils map to the 

geologic map, the geomorphic map, the vegetation map, 

and the cultural site maps for a comprehensive GIS of the 

area to investigate how the soils relate to the landscape. 

Park Physical Resource Concerns: 

The following were identified as concerns: 

• Loss of pastureland along river 

• Water supply and hydrology 

• Sediment loading in river behind three dams that 

created ponds 

• Nitrates in water 

• Spring locations 

• Restoration of prairie plants and soils 

• Ground Water Data 

The meeting then moved into the park itself. There was 

one bedrock outcrop found in the park in the stream 

bottom. It was Cretaceous sandstone lying 

unconformably on Precambrian crystalline rocks. 
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and other 

information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and affiliated Island 

Communities. 

Lyndon B. Johnson National Historical Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/024 

NPS D-83, February 2008 

National Park Service 

Director • Mary A. Bomar 

Natural Resource Stewardship and Science 

Acting Associate Director • Mary Foley, Chief Scientist of the Northeast Region 

Natural Resource Program Center 

The Natural Resource Program Center (NRPC) is the core of the NPS Natural Resource Stewardship and 

Science Directorate. The Center Director is located in Fort Collins, with staff located principally in 

Lakewood and Fort Collins, Colorado and in Washington, D.C. The NRPC has five divisions: Air 

Resources Division, Biological Resource Management Division, Environmental Quality Division, Geologic 

Resources Division, and Water Resources Division. NRPC also includes three offices: The Office of 

Education and Outreach, the Office of Inventory, Monitoring and Evaluation, and the Office of Natural 

Resource Information Systems. In addition, Natural Resource Web Management and Partnership 

Coordination are cross- cutting disciplines under the Center Director. The multidisciplinary staff of NRPC 

is dedicated to resolving park resource management challenges originating in and outside units of the 

national park system. 

Geologic Resources Division 

Acting Chief • John Vimont 

Planning Evaluation and Permits Branch Chief • Carol McCoy 

Credits 

Author • Trista Thornberry- Ehrlich

Review • Bruce Heise 

Editing • Diane Lane and Sid Covington 

Digital Map Production • Georgia Hybels and Anne Poole 

Map Layout Design • Georgia Hybels
Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, CO 80225 

http://www.nature.nps.gov/geology/inventory/ 

(303) 969-2090 

EXPERIENCE YOUR AMERICATM 

National Park Service 

U.S. Department of the Interior