Geologic History of Texas Lab Exam

Earth & Space ScienceWednesday 27 February 2013

For your Reference…

1. These dunes along Padre Island formed

A. 1.8 Billion years ago

B. 542 million years ago (MYA)

C. 65 MYAD. 1 MYAE. Less than 12,000

years ago

2. This is an aerial view of the Odessa Meteor Crater in Ector County. If it impacted 63,500 years ago, what period would this have

happened in?

A. PermianB. Triassic C. JurassicD. TertiaryE. Quaternary

3. If the Russian meteor from 2 weeks ago was as large as Tanguska, how old will you be when another one of this size occurs?

A. ~ 19B. ~ 28C. ~ 117D. ~1018E. fossilized

4. The Monahans Sandhills of West Texas represent one of the few instances where sediments are being

deposited without water. In what geologic period was this climate prevalent in Texas?

A. CretaceousB. OrdovicianC. TertiaryD. TriassicE. Pennsylvanian

5. The Inner Space Caverns in Georgetown are a spectacular example of…

A. Oil trapB. PinchoutC. InterfaciesD. Karst

TopographyE. Overthrust

Fault

6. Where can you go to see the Ouachita Mountains today?

A. Eastern OklahomaB. DallasC. Texas Hill CountryD. Enchanted RockE. Padre Island

7. Here are some Texas state parks. Which one has the oldest rock?

A. Palo Duro CanyonB. Enchanted RockC. Pedernales FallsD. Dinosaur Valley E. Davis Mountains

8. Austin Chalk is a tight-grained limestone, widespread across central Texas. The Woodbine is a porous sandstone found in Northeast Texas. San Andres is a widespread dolostone in West Texas, while the Wolfcampian is a porous mixture of limestone and dolostone. The Louann Salt is what forms the salt

domes in Southeast Texas. Which one makes a good caprock?

A. Austin ChalkB. Woodbine SandstoneC. San Andres DolostoneD. Wolfcampian Dolostone/LimestoneE. Louann Salt

This is a diagram of Pilot Knob, an extinct volcano located southeast of Austin along the Balcones Fault Zone.

9. What creature may have witnessed the eruption? A. TrilobiteB. DimetrodonC. T-rexD. Woolly MammothE. Dunkleosteus10. What kind of faulting is depicted? F. NormalG. ReverseH. Lateral I. OverthrustJ. Growth

Here at Pedernales Falls State Park is an excellent example of a gap in a geologic sequence .

11. What kind of unconformity is this? A. AngularB. ButtressC. Nonconformity D. DisconformityE. Paraconformity

Marble Falls Limestone Glen Rose Limestone

12. Which oil formation contains the oldest oil? B 13. The youngest? D

A. Spraberry B. Panhandle WestC. GiddingsD. SpindletopE. East Texas

14. In what age formation is most coal mining currently taking place in Texas?

A. PennsylvanianB. PermianC. CretaceousD. EoceneE. Pleistocene

15. Here at Dinosaur Valley State Park, Carnosaur tracks have been preserved in Glen Rose Limestone. What did this area look like back then?

A. Sandy beachB. Tropical tidal mud flatC. Volcanic mudflowD. Tropical RainforestE. Mountain valley16. What great evolutionary achievement is

represented in these tracks? A. Amniotic eggB. Bipedal gaitC. Carnivorous dietD. Specialized dentitionE. Amphibious lifestyle

17. Why is there so little Triassic material in the Gulf basin?

A. It was all washed away when the Gulf of Mexico began to form. B. No more trilobites were around to form greensand. C. We simply can’t see what’s under the salt because salt reflects seismic waves. D. The salt domes brought the older sediments to the surface to be eroded away. E. Being in the middle of Pangea, Texas was in the middle of a very arid desert, with no water to

transport sediments to the sea.

18. These salt domes are located hundreds of miles inland. What do they tell us about Texas’ geologic past?

A. The early Gulf of Mexico once spread across all of East Texas.

B. All of East Texas was a vast salt flat.

C. South America began splitting from North America at this point, opening up rift lakes and seas that would occasionally evaporate, leaving behind salt deposits.

D. All of the aboveE. None of the above

19. The Marathon-Ouachita Structural Front represents…

A. The site of an ancient mountain range

B. The site of the Balcones Fault Zone

C. Ancient continental margin of North America

D. All of the aboveE. None of the above

20. Which of the following can be obtained from a salt dome? (mark all that apply)

A. Nuclear fuelB. SheetrockC. Table saltD. MatchsticksE. Water

21.If you ran an exploratory well in the DFW area, and you hit metamorphic rock, which formation would you know you’ve drilled into?

A. Fort Worth BasinB. East Texas BasinC. Washita GroupD. Texas CratonE. Ouachita Foldbelt

22. The Texas Craton was formed as part of the Grenville Orogeny, a period of mountain-building that is exposed in the Llano Uplift of Central Texas. The Ellenberger Formation represents an ancient sea that covered Texas sometime later. If we were to go back in time from the present day as far as the time that is missing between these two periods, what would be the principal lifeform on the planet?

A. DinosaursB. TherapsidsC. TrilobitesD. DickinsoniaE. Stromatolites

23. This iconic Texas landmark is actually the largest of its kind on Earth. What is it?

A. BatholithB. Fossil ReefC. Ancient deltaD. Salt domeE. Volcanic

neck

24.When did the oil reservoirs of the Permian Basin form in relation to sea-level fluctuations in the Absaroka Sea?

A. During a transgression

B. During a regression

25. Which oil trap is typical of the East Texas Oil Field?

A. 1B. 2C. 3D. 5E. 6

(These are your answer choices!)

(a - oil; b – sand; c – shale)

26. Here are some Texas state parks. In which one can one find volcanic rock?

A. Palo Duro CanyonB. Enchanted RockC. Pedernales FallsD. Dinosaur Valley E. Davis Mountains

27. I’ve oohhed and ahhed at the fabulous travertine formations of Carlsbad Caverns and inspected coral while hiking along the crest of Guadalupe Peak. What rock makes up the Guadalupe Mountains?

A. GraniteB. GneissC. LimestoneD. SandstoneE. Halite

28. Here’s a photo of the representative formations that make up Palo Duro Canyon. Which one would be the most likely to contain a Dimetrodon?

A. Quartermaster Redbeds from the PermianB. Dockum Group Shales from the TriassicC. Ogallala Sandstone from the PlioceneD. All of the aboveE. None of the above

Quartermaster Formation

Dockum Group

Ogallala Formation

Where mountains collide: The Geologic tale of Big Bend

For a period of at least 200 million years, ending some 300 million years ago in the Paleozoic Era, a deep-ocean trough extended from present-day Arkansas and Oklahoma into the Big Bend region of far West Texas. Sediments from highlands to the north accumulated in that trough to form layers of gravel, sand and clay. With the passing of time, these layers became sandstone and shale beds. About 300 million years ago these strata were “squeezed” upward by collision with a continent to the south to form the ancestral Ouachita mountains. Subsequent erosion over an interval of 160 million years left only the roots of those mountains visible. These remnants may be observed today in the Ouachita Mountains of southeastern Oklahoma, in the immediate vicinity of Marathon, Texas, and in Big Bend National Park near Persimmon Gap.

A warm, shallow sea invaded the Big Bend during the Cretaceous Period, some 135 million years ago, providing the setting for deposition of lime mud and the remains of sea-dwelling organisms such as clams and snails. Limestone layers formed from those shallow muds are now visible throughout much of the Big Bend. They comprise the dramatic walls of Santa Elena, Mariscal and Boquillas canyons, the entire range of the Sierra del Caballo Muerto (Dead Horse Mountains) and the magnificent cliffs of the Sierra del Carmen in Coahuila, Mexico, towering above Rio Grande Village. Approximately 100 million years ago the shallow Cretaceous sea began a gradual retreat to its present location, the Gulf of Mexico. Sandstone and clay sediments that formed along the retreating shoreline are found in lowlands surrounding the Chisos Mountains. Shallow water strata of this episode contain the fossil remains of oysters, giant clams, ammonites, and a variety of fishes and marine reptiles. Near-shore deposits in Big Bend have yielded petrified wood, fossil turtles and crocodiles--one almost 50 feet long! Deposits from further inland contain fossil remains of a variety of dinosaurs. Perhaps the most famous of Big Bend’s fossil treasures from this period is the giant flying reptile, Quetzalcoatlus northropi, with a wingspan over 35 feet. (A replica of the bones of one wing is now on exhibit at the Panther Junction Visitor Center.)

Near the end of the Cretaceous Period, a west-to-east compression of the earth’s crust marked the beginning of the second major mountain-building period in Big Bend. This compression, which began in Canada, moved gradually southward, uplifting and folding ancient sediments to form the Rocky Mountains. In Big Bend National Park, Mariscal Mountain represents the southernmost extension of the Rockies in the United States. Broad uplift punctuated by upward folding exposed both the erosion-resistant lower Cretaceous limestones and the less resistant overlying sandstones and clays to the onslaught of erosion. Limestone cliffs throughout the region continue to be eroded today; most of the more easily removed sandstone and clay is gone from the mountains.

• For almost 10 million years after uplift ended, non-marine sediments of the Tertiary period constitute the only record of events in the Big Bend. Dinosaurs had long been gone from the land, their places taken by a proliferation of mammals, many of whose remains have been found in Big Bend...horses, rhinos, camels and rodents, as well as fossils of the plants on which they thrived. All was not to remain quiet for long. Near the present northwest boundary of Big Bend National Park, the first of a long series of volcanic eruptions occurred approximately 42 million years ago. Upwelling magma lifted the mass now known as the Christmas Mountains, fracturing and weakening overlying strata, allowing massive outpourings of lava to spread across the land. The oldest volcanic rocks in Big Bend owe their origins to this eruptive cycle. Between roughly 38 and 32 million years ago Big Bend itself hosted a series of volcanic eruptions. Initial activity in this cycle centered in the Sierra Quemada, below the present South Rim of the Chisos Mountains. Subsequent volcanic activity at Pine Canyon, Burro Mesa, near Castolon and elsewhere in the park is responsible for the brightly colored volcanic ash and lava layers of the lower elevations and for most of the mass of the Chisos Mountains.

Volcanic activity was not continuous during these eruptive cycles. Periods of hundreds of thousands or perhaps millions of years passed between eruptions. During the quiet interludes the forces of erosion carved new landscapes, many of which were destined to be buried under layers of ash and lava from later eruptions. Life returned to the land only to be displaced by future eruptions. Elsewhere in the Big Bend rising magma sometimes failed to reach the surface. Instead, it spread within existing layers of rock, uplifting and fracturing overlying strata. Once the magma cooled and crystallized it formed solid masses of erosion-resistant intrusive igneous rock which have now been exposed by erosion of the overlying material. Maverick Mountain, the Grapevine Hills, Nugent Mountain and Pulliam Ridge are among many examples in Big Bend of such “frozen” magma chambers.

Beginning some 26 million years ago, stresses generated along the West coast of North America resulted in stretching of the earth’s crust as far east as Big Bend. As a result of these tensional forces fracture zones developed which, over time, allowed large bodies of rock to slide downward along active faults. The central mass of Big Bend National Park, including the Chisos Mountains, from the Sierra del Carmen to the east to the Mesa de Anguila to the west comprises such a block of rocks dropped downward by faulting. Direct evidence of this faulting is readily observed at the tunnel near Rio Grande Village. There the limestone layer through which the tunnel passes is the same layer that forms the skyline of the Sierra del Carmen to the east, dropped down over 4800 feet by faulting. To the west, at the mouth of Santa Elena Canyon the highest elevation rises 1500 feet above the river, while at the parking area the same layer lies some 1500 feet below the surface. Displacement along these faults did not occur in a single event, rather in a series of lesser episodes of faulting punctuated by earthquakes. The 1995 magnitude 5.6 earthquake near Marathon, Texas, 70 miles north of Panther Junction indicates that the responsible stresses are still active. The western slopes of the Chisos Mountains provide evidence of additional activity within the same fracture zones. Near the old ranch on the Ross Maxwell Scenic Drive stand a number of parallel ridges to the east of the road. These ridges are the eroded remains of tabular intrusions of magma along the Burro Mesa fault. The layers of volcanic ash into which the magma intruded are being actively removed by erosion, leaving the more resistant “dikes” of intrusive rocks standing in bold relief.

Mountain building by compression, volcanism and tension all served to form the framework for today’s landscapes in Big Bend National Park. Erosion of higher lands resulted in the filling of surrounding basins. Eventually basins from El Paso to Big Bend were filled and subsequently linked by the Rio Grande. Achieving through-flow to the Gulf of Mexico only within the last 2 million years, the Rio Grande ranks as the youngest major river system in the United States. Once established, the Rio Grande served, and continues to serve, as the conduit for material removed by erosion. The processes of erosion comprise the most active aspect of Big Bend’s geology today.

29. At Big Bend National Park, two great mountain ranges meet. What are they?

29. At Big Bend National Park, two great mountain ranges meet. What are they?

A. AppalachiansB. OuachitasC. CascadesD. RockiesE. Sierra Nevada

30. What is a danger from fracking? (mark all that apply) A,B,E31. What is a benefit? (mark all that apply) D A. Increased health risksB. Water pollutionC. Higher natural gas pricesD. Lower natural gas pricesE. Increased air & noise

pollution from increased truck traffic

32. We lie right on top of the 3rd largest aquifer in the nation, but area governing bodies are trying to limit public use of it. Why?

A. It’s too saltyB. It’s too pollutedC. We need to save it for

emergency use D. Overuse and

overdrilling in the past has led to subsidence

E. It’s a government conspiracy and coverup.

Here at Pedernales Falls State Park is an excellent example of a gap in a geologic sequence .

33. Which rock layer is older? A. Marble Falls

LimestoneB. Glen Rose

Limestone34. Which would you

expect to find dinosaur tracks in ?

C. Marble Falls Limestone

D. Glen Rose Limestone

Marble Falls Limestone Glen Rose Limestone