Geologic Wonders of Central Texas Produced by and for the Outreach Lecture Series of the Environmental Science Institute. We request that the use of any of these materials include an acknowledgement of Dr. Leon E. Long and the Outreach Lecture Series of the Environmental Science Institute of the University of Texas at Austin. We hope you find these materials educational and enjoyable. by Dr. Leon E. Long Outreach Lecture Series Volume 17
Geologic Wonders Of Central Texas Geologic Wonders Of Central Texas Department of Geological Sciences Dr. Leon E. Long
image 1 - Two divisions of Texas along an S-shape line that passes through Austin
image 2 - Texas average annual rainfall; climatic impact on the landscape
image 3 - Geologic map of Texas
image 4 - North Central sub- province North-Central Texas Austin
image 5 - Gulf Coastal Plain sub- province Gulf Coastal Plain Austin
image 6 - Trans-Pecos sub- province Trans-Pecos Austin
image 7 - High Plains sub- province Austin
image 8 - Edwards Plateau sub- province Austin
image 9 - Cretaceous interior Seaway
image 10 - Llano Uplift sub- province Austin
image 11 - Orientation map showing Austin astride (or near to) three sub-provinces
image 12 - Llano Uplift basement geology
image 13 - Geologic timescale; ages of formation of rocks in the Llano Uplift
image 14 - Inverse geologic timescale; ages of erosion or non- deposition in the Llano Uplift
image 15 - Orientation; Enchanted Rock batholith within the Llano Uplift
image 16 - Oblique aerial photo of Enchanted Rock
image 17 - Major minerals in granite
image 18 - Igneous intrusive origin of granite
image 19 - Photo from top of Enchanted Rock showing adjacent exfoliation dome
image 20 - Photo of exfoliation sheets popping off exfoliation sheet
image 21a - Photo of joints in granite; joints v. faults
image 21b - Photo of joints with labels
image 22 - Weathering attack of granite
image 23 - Photo of rounded granite boulder
image 24 - Vertical aerial photo of rounded exfoliation domes at enchanted rock
image 25a - Photo of view to the south; Cretaceous escarpment; rate of weathering of granite
image 25b - View to the south with labels
image 26a - Photo of view to the east; Riley Mountains
image 26b - View to the east with labels
image 27 - Ages of rocks symbolized in the preceding image
image 28 - Geologic map of Enchanted Rock and vicinity
image 29 - Map showing all 3 types of geologic contac: depositional (Cretaceous escarpment), fault (Riley Mountains), and igneous intrusive (Enchanted Rock batholith)
image 30 - Stage I of landscape development (form the rocks)
image 31 - Stage II (deform the rocks) and Stage III (erode the rocks); inversion of topography
Image 32a - Fault drag at Hoover Point
Image 32b - Fault drag at Hoover Point with text
Image 33 - Fault Zone
image 34 - Geologic map showing Sandy Creek
image 35 - Landscape development I
image 36 - Landscape development II
image 37 - Landscape development III
image 38 - Landscape development IV
image 39 - Landscape development V
Image 40 - Braided stream vs. meandering stream
image 41 - Granite weathering into grus
Image 42 –Granite grus
Image 43 – Sandy Creek
Image 44 – Orientation map of Austin and vicinity
image 45 – Bedrock in Austin on two sides of Mt. Bonnell Fault
Image 46 - Photo of Pilot Knob
image 47 - Pilot Knob volcano
Image – Photograph of modern volcano erupting
image 48 - Pilot Knob then and now
Image 49 – McKinney Falls
Image 50 – Close-up of falls
Image 51 – Layer cake stratigraphy
Image 52 – Ordinary rock?
Image 53 – Fossil of an ammonite!
image 54 - Ammonite
Image 55 - Development of stream terraces
Image 56 - Topographic contour map, McKinney Falls State Park
Image 57 -Stream terrace deposits, McKinney Falls State Park
Image 58 - Recent floodplains, Austin and vicinity
Image 59 - Older terraces
Image 60 - Even older terraces
Image 61 - Highest, most ancient stream terraces
Image 62 - Austin airports on terraces
Image 63 - View from Mt. Bonnell
Image 64 - Stair step topography
Image 65 - Desiccation cracks
Image 66 -Texas Valley Country
Image 67 - Long profile of stream
Image 68 - Fossil and active meanders
Dr. Leon Long Professor and The Second Mr. and Mrs. Charles E. Yager Professorship and member of the Academy of Distinguished Teachers Dr. Leon Long is a geology professor at the University of Texas at Austin whose research interests include isotope geology, especially to use naturally occurring radioactivity and its daughter products as a geologic clock, and as a geochemical tracer. He is also interested in applying the Rb- Sr isotopic age method to clay minerals with a possibility of dating when weathering had produced an ancient soil zone. As the department’s generalist, Dr. Long has also written the textbook for the introductory course.