GUIDEBOOK Canyon Dam Spillway Gorge 29 and Natural Bridge Caverns Geologic Excursions in the GUIDEB O OK Zone, Central Canyon Dam Spillway Gorge 29 and Natural Bridge Caverns Geologic Excursions in the Balcones Fault Zone, Central Texas

Canyon Dam Spillway Gorge and Natural Bridge Caverns, in Comal County, Texas, are the focus of this new guidebook from the Bureau. Besides the geologic explanations of these two remarkable sites, a road log to and from Austin discusses various natural resources as well as cultural and historical sites along the route. Special attention is given specific localities that provide insights on ancient geologic processes, landscape evolution, and aquifer development near the Balcones Escarpment between Austin and San By Antonio. This guidebook will be of interest to anyone C. M. Woodruff, Jr., Edward W. Collins, Eric C. Potter, and Robert G. Loucks curious about this beautiful part of Texas. Bureau of Economic Geology Scott W. Tinker, Director The University of Texas at Austin

ORDER TODAY! $ (Order Form on back) 20

98° W

INTERSTATE 35 S H 1 3 0 U S

1 US 8 3 79 A

Lake Travis

US S H 183 1

3 US 0 281 S H US 0 7 6 290 1 3

p o TRAVIS CO. o 1

L p HAYS CO. o o L Austin Johnson About the Authors US BS 290 City 1 p o o US L 290 SH ABIA 71

SH 45 21 SH

BLANCO CO. KENDALL CO. US 281 30° N INTERSTATE 35 . US O 183 30° N C is a researcher at BEG, a consulting L Charles M. (“Chock”) Woodruff L E W LD SMS HAYSA CO. C Lockhart San Marcos Canyon geologist, and a Senior Lecturer in UT’s Department of Civil, Architectural, Lake Stop 1

SH 0 S 46 13 3 H Boerne M H CO AL 2 S 8 1 0 CO. CS H and Environmental Engineering. His work on the geology of Central Texas S R BEXA CO. Stop 2 New Luling

INTERSTATE Braunfels US INTERSTATE 10 90 10

16 604 spans more than four decades. SH p 1 UADALUPE CO. Loo G Barton Springs INTERSTATE Seguin BS SAIA 35 INTERSTATE 10 CS Comal Springs SMS San Marcos Springs Spring location Eddie Collins is a Research Scientist Associate at the BEG, specializing in Approximate trace of Balcones Escarpment

INTERSTATE US US INTERSTATE 37 87 Selected fault traces 90 410 geologic mapping. Austin–Bergstrom ABIA International Airport

INTERSTATE US 35 oop 16 SAIA San Antonio L 04 181 International Airport US 281 QAe5091 Eric Potter recently retired, served for 15 years as the associate director 0 10 mi 98° W 0 15 km nty) and leading the Bureau’s Energy Research program. Comal County and major roads between Austin (Travis Cou, and major Figure 1. Regional map showing stop locations in ed faults, a generalized trace of the Balcones Escarpment San Antonio (Bexar County). Also shown are select spring locations. Bob Loucks is a Senior Research Scientist at the BEG. to design: the overflow there prevented the dam from unnamed, high-gradient tributary to the Guadalupe - being overtopped, with likely disastrous consequences. River. Apparently this construction was done with Still, the redirected floodwaters stripped vegetation, out regard to the impact on the small downstream soil, and considerable amounts of bedrock, as well as watershed should an overtopping occur. But in an destroying a bridge and roadway downstream. engineering context, the spillway functioned according Order online http://begstore.beg.utexas.edu/store/vi | Canyon Dam Spillway Gorge and Natural Bridge Caverns Order Form

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