Geology Question for Big Ed

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Geology Question for Big Ed

Post by dbhguru » Mon Aug 08, 2011 8:41 am

Ed,

While on the Parkway, Monica made an excellent book purchase. Its title is 'Mount Mitchell & the Black Mountains - An Environmental History of the Highest Peaks in Eastern America". Author Timothy Silver is a professor at Appalachian State University in Boone, NC. He is an engaging writer and a consummate scholar. I highly recommend the book. Can't say enough good about it.

On page 3, Silver discusses the geology of the Blacks. He describes the break apart of Pangaea between 180 and 200 million years ago in the formation of the modern day southern Appalachians. This is the history I know. However, he states in paragraph 3

Long after Pangaea dividedm periodic episodes of folding and uplift continued to push ancient rock formations to the surface. About 65 million years ago one such geologic event exposed a jagged mass of gneiss and schist that had been buried since the earliest phases of continental movement. Between 39 Deg 5 min and 39 deg and 7 min north latitude (just north of the modern city of Asheville) some of the new mountains formed a fifteen -mile-long semicircle that vaguely resembles a fishhook. The odd formation did not conform to the general southwest-northeast sweep of the Appalachians. Instead, the peaks emerged as a cross range, extending at a sharp angle north an slightly west from the Blue Ridge.

This is the first account of the Blacks as being substantially younger than the main body of the Blue Ridge. Now, I'm wondering if the adjacent Great Craggies were formed at or near the same time, or at a significantly different time. Have you read much on the geology of the southern Apps? I'm really curious about what constitutes truly separate geological events in the jumble of range names we encounter in the southern Apps. We have Blue Ridge, Blacks, Craggies, Nantahalas, Cowees, Pisgahs, Cohuttas, Snowbirds, Unakas, Smokies, Unicois, Swannanoas, etc. My assumption heretofore as to what constituted separate named ranges was largely a product of the speed of erosion. It appears that the actual formation of the southern Apps occurred over a much longer time period and included many separate sub-events, some volcanic, some faulting and folding. Any thoughts on the Craggies?

Bob
Robert T. Leverett
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Re: Geology Question for Big Ed

Post by edfrank » Mon Aug 08, 2011 3:07 pm

Bob,

The history of Appalachian Mountains is extremely complex and not fully understood. I am sure that Dr. Timothy Silver (History) has doen a reasonable job of interpreting the geology as known by people with whom he has discussed the issue. There have been a couple of conferences dealing specifically with the geology of this region in the last ten years:

in 2006: http://gsa.confex.com/gsa/2006SE/finalp ... _16595.htm Recent Advances in Western Blue Ridge Geology
in 2001: http://gsa.confex.com/gsa/2001SE/finalp ... ion_41.htm Cenozoic Evolution of the Appalachian Orogen

The GSA is the primary geology group in the US and session sere organized around these topics. So these are not crackpot ideas, but I am not sure how well they have been accepted in the overall geologic community at this time. The entire blue ridge consists of a series of faults that have occurred since the late neoproterozoic.

Aber ( http://academic.emporia.edu/aberjame/st ... palach.htm ) writes: "Piedmont -- Stretching from Alabama to New York, the Piedmont is a plateau of moderate elevation (150-300 m) that forms the eastern portion of the mountain system. It consists of varied crystalline metamorphic and igneous rocks of Paleozoic age. Many of the rocks began as marine sediments and volanic deposits--typical oceanic crust--that were deformed and metamorphosed mostly to the greenschist facies of chlorite and biotite schists and slate. Numerous granite intrusions form domes within the Piedmont, and narrow belts of serpentine are common. All Paleozoic and older rocks of the Piedmont Province are now thought to be completely allochthonous thrust masses.

Blue Ridge -- Upthrust Proterozoic basement rocks form a relatively narrow ridge separating the Piedmont from the Valley and Ridge provinces. The boundary between the Piedmont and Blue Ridge is marked by the Brevard Fault zone in the southern Appalachian. This fault zone contains remnants of unmetamorphosed sedimentary rocks derived from the deep décollement beneath the Piedmont Province. Like the Piedmont, the Blue Ridge is considered to be allochthonous."

The dating of many of the multiple pieces of the puzzle that is the Blue Ridge is still up for debate. Alienkoff (2006) wirtes: "The Ocoee Supergroup, western Blue Ridge of TN/NC, is a sequence of clastic (coarse to fine), mainly arkosic, rift-facies metasedimentary rocks. It is subdivided into the Snowbird, Great Smoky (GSG), and Walden Creek (WCG) Groups, which are separated by major thrust faults." and "We conclude that the Ocoee Supergroup was deposited between about 930 and 700 Ma (possibly at about 850 Ma) and was metamorphosed at lower greenschist facies several times in the Neoproterozoic. The ~ 570 Ma thermal event corresponds to the period of Catoctin volcanism in central Virginia to Pennsylvania. However, the older thermal events of ~855, ~780, ~685, and ~640 Ma are not known in Laurentian Neoproterozoic rocks."

Thgpen (2006) writes; "Most OSG rocks immediately south of the GSMNP reveal at least three periods of deformation. An early event likely related to the Taconic (Middle Ordovician) orogeny produced folding, faulting, cleavage development and metamorphism, while a later event interpreted as the Alleghanian (Pennsylvanian-Permian) orogeny involved brittle faulting and folding. Rocks of the study area are deformed by at least three periods of faulting and folding (F1-F2) and one regional metamorphic cleavage-forming event (S2). "

Kristopher (2006) writes: "The nature of the contact between the Great Smoky (GSG) and Snowbird (SG) Gps. has long been an enigma for interpretation of the tectonic evolution of the southern Appalachian Blue Ridge. The contact has been interpreted as a premetamorphic fault (“Greenbrier Fault”), a lithologic contact, or a fault-reactivated contact. Prograde and retrograde metamorphism and deformation complicate the interpretation."

Sotuhworth (2006) writes: "In the eastern part of the Great Smoky Mountains National Park (GSMNP), the Greenbrier fault (GF) places rocks of the Neoproterozoic Great Smoky Group (GSG) in the Greenbrier thrust sheet (GTS) onto older Mesoproterozoic rocks and Neoproterozoic rocks of the Snowbird Group. At the type-locality, the GF is a zone of brittle deformation 1 to 30 m thick that truncates bedding and stratigraphy in both the upper and lower plates."

These sample represent some of the complexities associated with interpretations. The ages of faults are determined by the age of the rocks they cut through - they must be younger than the rocks they cut, and they must be older than the sediment deposited on top of them and older than the faults that cut through them. Periods of metamorphism are usually associated with movement or creation of various fault systems. The dates of the periods of metamorphism and temperatures can be accurately measured by the minerals present and the resetting of certain characteristics in the minerals, such as fission tracts. So these metamorphic episodes are used to constrain the periods of faulting. Similar logic and dating can be applied to episodes of igneous intrusion into the overlying rocks.

So there isn't any real doubt that the core of the activity was late neoprotozoic to Paleozoic, but activity has continued to occur sporadically since. The big deal with respect to Cenezoic (65 mya) activity is that there are pockets of Cenezoic sedimentary rocks scattered here and there across the Blue Ridge.

Prowell (2006) writes: "The height and morphology of the present-day southern Appalachian Mountains (as defined physiographically) are attributed traditionally to Paleozoic and early Mesozoic tectonism and differences in the resistance to erosion of the various Precambrian and Paleozoic rocks that comprise the province. The present configuration of the Fall Line, combined with the occurrence of Cretaceous and younger marine deposits up to 300 m (1,000 ft) above present sea level indicate that Coastal Plain strata once covered parts of the mountain chain, which have been regionally uplifted to their present positions. Remnant Cretaceous and lower Cenozoic strata are preserved at elevations up to +685 m (+2,250 ft) in numerous fault-bounded and(or) sinkhole sediment traps as far inland as northern Georgia and Alabama, southeastern Tennessee, western Virginia, and Pennsylvania. The sediments in these traps are most likely the preserved parts of an extensive blanket of Coastal Plain strata that was derived from regional erosion. The sediment traps, which are filled with fluvial strata as much as 100 m (325 ft) thick uncommonly contain carbonaceous beds. Palynological age assignments of pollen in these beds indicate that they are correlative with Coastal Plain formations hundreds of kilometers seaward. The ages assigned to the sediments in these traps range from Late Cretaceous to middle Eocene. If the sediment trap strata are part of a regional cover that was once continuous across the southern Appalachian Mountains, then the uplift of the present-day southern Appalachians must post-date the youngest palynological age (middle Eocene). Applying minimal published erosion rates (3 m/m.y.) for the Appalachian Mountains, these deposits would have been completely eroded during the last 33 m.y. given their present thickness (< 100 m). Therefore, the fact that they exist at all indicates that: (1) they were once covered by a much thicker sedimentary cover, and(or) (2) their uplift, along with that of the Appalachians, must be considerably more recent than Eocene. This new evidence suggests the intriguing possibility that the Appalachians are not Paleozoic mountains, but rather late Cenozoic mountains comprised of Precambrian and Paleozoic rocks."

This is perhaps too bold of a statement for the mountains overall as there is strong evidence of the mass of the mountains dating from the Paleozoic, but the southern end of the Appalachian chain could be substantially younger.

Clark (2001) talks of Tertiary uplift in the Peidmont Region; "Mesozoic extensional faulting and basin formation provide a mechanism for escarpment formation and the lowering of the Piedmont land surface, allowing Cretaceous to Late Tertiary seas to at least partially cover the present-day Piedmont. Substantial Tertiary uplift of the margin could account for the removal of this cover and exposure of the Blue Ridge Escarpment and Piedmont. Continued uplift at a subdued rate may continue to be a driving force for the short wavelength relief of the escarpment and the southern Blue Ridge. Although the exact timing and magnitude of the uplift continues to be questionable, it is believed to have been most likely centered around the major Oligocene and Early Miocene unconformity ending by the time of deposition of the Upland Unit (Mid-Miocene) traceable from New Jersey to Georgia in various stratigraphic units. Estimates for the magnitude of uplift are highly dependent on the former extent of sea level, but are thought to be of approximately 500-1000 m in vertical crustal motion." So the region is still active.

I have not in my brief review of the literature available on the internet found any specific information on the Blacks nor the Craggies. I will keep looking.

Ed
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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Re: Geology Question for Big Ed

Post by edfrank » Mon Aug 08, 2011 3:22 pm

Bob,

As I reread the post above I see that I really did not answer your question. I am currently out of the loop in terms of what is happening in Appalachian tectonics. I am in the wilds of Pennsylvania and do no regularly read, nor even have easy access to the current journals and publications. I am not part of the ongoing geologic discussions. Even when I was in school my focus was on kart processes and Caribbean tectonics rather than the Appalachians. That being said I can offer this. There seems to be good evidence that regional uplift was taking place in the southernmost Appalachians during the late Cretaceous to mid-Tertiary period. It is not unreasonable that a part of the chain farther north, such as the Blacks might also have undergone uplift concurrently with these more southerly events. The same would be possible for the Craggies, but I have no references on-hand to even suggest or to dispute the idea they might also be a younger range. I can look online for more information or maybe you could contact Dr. Silver who has researched this topic. http://www.history.appstate.edu/faculty ... tim-silver

Ed
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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Re: Geology Question for Big Ed

Post by dbhguru » Mon Aug 08, 2011 3:48 pm

Ed,

Thanks a bunch. Great stuff! I don't really understand it, but get glimpses now and then. I intend to read through the material again.

Simplistic explanations of the formation of the Appalachians that popular descriptions presented in pamphlets and in kiosks promulgate lead us to imagine a big, more or less continuous, uplift occurring somewhere between 230 and 400 million years ago, and then a slow wearing down from erosion ever since, harder rock types resisting the erosion to provide the relief we see today. But the real story is so many, many times more complicated - and interesting. Geology is way, way cool. The gap between the Craggies and Balsams lies at 5,200 feet. One would never know that they had passed from one range to another, were it not for the changes in vegetation. That also is way, way cool.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

Joe

Re: Geology Question for Big Ed

Post by Joe » Tue Aug 09, 2011 6:22 am

dbhguru wrote:Ed,

Thanks a bunch. Great stuff! I don't really understand it, but get glimpses now and then. I intend to read through the material again.

Simplistic explanations of the formation of the Appalachians that popular descriptions presented in pamphlets and in kiosks promulgate lead us to imagine a big, more or less continuous, uplift occurring somewhere between 230 and 400 million years ago, and then a slow wearing down from erosion ever since, harder rock types resisting the erosion to provide the relief we see today. But the real story is so many, many times more complicated - and interesting. Geology is way, way cool. The gap between the Craggies and Balsams lies at 5,200 feet. One would never know that they had passed from one range to another, were it not for the changes in vegetation. That also is way, way cool.

Bob
Bob, I'm only a guy who likes geology- never even took a course, but I have read several college textbooks so I have some idea of the subject- my understanding is that after the original uplift of the mountains, and their wearing down- the land periodically uplifted in stages, because of the principle of eustatic equilibrium (like if the top of a floating cork were to wear down, the cork would rise). Each time it rises- rivers cut down, and if it stops rising for awhile, the rivers cut flood plains, then when the next rise occurs, the river will cut into those old flood plains-- apparently it's possible to detect a series of staircase like levels througout the mountains which record the uplifts and river cuttings. The staircase effect is best seen in the south where the glaciers didn't go- the staircases happened in the north too, but the activity of the glaciers has obscured them. As I climb around our northern mountains and come across a nice almost flat area I always wonder if that level represents some very ancient flood plain.

The originally worn down almost flat landscape is called a peneplain- which was at first thought to be of Cretaceous age but that's now debated. Remnents of that uplifted peneplain can still be seen in western New England. If you are at the top of any ridge and look in any direction- it seems that the tops of all the ridges are all about the same level- which is true because that level is the peneplain which in the Berkshires is about 2,000'- but as you go easterly it's lower- any hill rising above that ancient peneplain is called a monadnock after Mt. Monodnock which was the first example where this principle was discovered. So, much of our northern Applaachian landscape is an elevated flat surface cut down by rivers. When I first learned of this it really blew me away- because it reminded me of a college room mate who was an art major. One day I watched him work on a Japanase wood print. He began with a large flat piece of wood which he carved into. I didn't have a clue about art. I presumed that what he cut out was going to eventually make an image but no--- he said that the flattened surface that he left is what would result in an image after he rolled ink on it, then pressed paper on to the remaining parts of the flat surface.

So, when I ponder our landscape of western New England, I see it as a gigantic analogy to a Japanese wood print!

Also, as long as I'm rambling, the "Berkshire Massif" lying between the Housatonic and CT Rivers is analogous with the Blue Ridge - apparently most of the geologic features of western New England and eastern NY have analogies with the southern Appalachians.


As you say, geology is way cool. There is a beauty in looking at the mountains- their shape, colors, patterns, etc... but when you ponder how those shapes have changed over hundreds of millions of years- that make them seem alive and far more profound.
Joe

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Re: Geology Question for Big Ed

Post by dbhguru » Tue Aug 09, 2011 6:55 am

Joe,

Great explanation. We listen to the same Earth songs, but you here more of the melody. I'm trying to fine-tune my ear.

Every time Monica and I head west, one of the things I look forward to is seeing the patterns of deposition and folding the the rocks. What is especially exciting is that new data and interpretations reveal or at least give clues to on-going geological processes that make the land seem much more alive. The older view of eastern mountains was one of gradual erosion until everything ended up flat. But with the new theories on the Dacks being young, as opposed to old, I now get a head rush from visits.

Perhaps the Craggies and Blacks reflect the same geological processes and ages. I'd like to think so. The Craggies are far less well known than are the Blacks, but outstanding mountains, scenically and forest cover-wise.

Hey, can we get together this week for a filming exercise?

Bob
Robert T. Leverett
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Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Re: Geology Question for Big Ed

Post by edfrank » Tue Aug 09, 2011 8:26 am

Bob,

I have been looking for a good summary of the overall history of tectonics in eastern NA. I eventually found this good overview published as a field trip guide for parts of Virginia http://pubs.usgs.gov/circ/2004/1264/htm ... index.html :
1. Regional Tectonic History of Northern Virginia

By Richard Diecchio1 and Richard Gottfried2

1George Mason University, Fairfax, VA 22030.
2Frederick Community College, Frederick, MD 21702.

Introduction

The objective of this one-day field trip is to examine the field relations that allow us to characterize the major physiographic provinces of northern Virginia and to interpret the tectonic history of this area. We will visit outcrops in the Coastal Plain, Piedmont (including a Mesozoic basin), and Blue Ridge provinces (fig. 1), for the purpose of comparing and contrasting their geology.
fig1.jpg
We will discuss tectonic events in terms of the Wilson Cycle of ocean-basin opening (rifting) and closing (mountain building), the final product being the mountain belt. The Appalachian Mountains are an excellent example of the repetitive nature of the Wilson Cycle (fig. 2). The tectonic events we will discuss include (oldest to youngest) Middle Proterozoic (Grenville) mountain building, Late Proterozoic (Proto-Atlantic or Iapetus) rifting, Paleozoic Appalachian (Taconic, Acadian, Alleghanian) mountain building, and Mesozoic (Atlantic) rifting.
fig2a.jpg
fig2b.jpg
The dynamic nature of the Earth is a consequence of plate tectonics. These plates are made of rigid continental and oceanic lithosphere. This lithosphere overlies an asthenosphere that is in constant motion. The lithospheric plates experience tensional, compressional, and shearing forces that lead to processes such as rifting, collisional tectonics, and transform faulting. In the process, new ocean floor may be created as well as chains of volcanic islands, areas of earthquake activity, and new mountain ranges. The continents themselves may shift their position as plates move. All of this affects the shape of the land and the distribution of rocks, minerals, fossils, climate, and natural resources. Northern Virginia has experienced several major tectonic episodes that are now recorded in the local rock record and may be visited at many places. The sites to be visited on this trip are selected on the basis of their significance relative to the tectonic history. These sites also illustrate the field relations that allow the recognition of the relative timing of these events.
Geologic History

Over one billion years ago in the Mesoproterozoic, narrow strips of land (microcontinents, volcanic arcs, and suspect terranes) collided with and compressed the eastern edge of the then developing North American continent. The rocks from these events are part of the Grenville province of the Precambrian Canadian Shield of North America. This collision between proto-North America and other continents led to the formation of a supercontinent called Rodinia. The formation of Rodinia also resulted in the formation of a mountain range: the Grenville Mountains, now the Grenville province of the Canadian Shield. This mountain-building event is called the Grenville orogeny. Locally, these rocks are found in the Blue Ridge province and are considered to be the oldest rocks in northern Virginia. They are exposed at the surface only after much weathering and erosion of overlying younger rock. Magmatic processes that accompanied this orogeny produced molten rock that was injected into the crust. These igneous rocks, along with the sediments that were eroded from the eastern margin of the Precambrian shield before this collision, were deformed and metamorphosed. We will see metaigneous rocks of Grenville age below the unconformity at Stop 9.

Following the Grenville orogeny, tensional forces associated with changes in mantle convection and (or) other processes led to a breakup of the Rodinian supercontinent. This latest Precambrian (Neoproterozoic) and Early Cambrian rifting led to the opening of the Proto-Atlantic or Iapetus Ocean that predates the Atlantic Ocean. Basaltic rocks that formed during this rifting (and were subsequently metamorphosed during the Paleozoic) are now part of the Catoctin Formation and will be visited at Stop 8. During rifting, fragments of the Grenville continental crust were broken off and became islands, later to be reunited with North America by subsequent closure of the ocean. The Goochland terrane of the Piedmont province may be one of these Grenville fragments (Spears and others, this volume).

As the Iapetus Ocean continued to widen, the rift margin became passive. Sediment continued to be deposited on the eastern edge of the continent, and a broad clastic shelf developed (Chilhowee Group). As the Grenville Mountains were eroded during the Cambrian, the source of clastics diminished and deposition of limestones predominated into the Early Ordovician. Locally, these limestones can be seen in the Frederick Valley and the Shenandoah Valley but will not be seen on this trip. Information about this part of the tectonic history of Virginia can be found in Fichter and Diecchio (1993) and in the additional resources listed at the end of this field guide. During the early Paleozoic the east coast of North America was aligned parallel to the equator that passed through the central part of the United States, roughly coincident with the present-day longitude of Kansas.

During the Middle Ordovician, the plate movements reversed, Iapetus began to close, and once again, continental plates began to converge. As Gondwana approached North America, a subduction zone formed and a volcanic arc complex developed off the east coast of North America. Continental fragments like the Goochland terrane (Spears and others, this volume), that had previously detached from North America, were now caught along with the volcanic arc between North America and Gondwana. Over time, the volcanic islands and continental fragments were thrust back onto North America, eventually to become today's Piedmont terrane. The carbonate and clastic rocks that were deposited on the eastern edge of North America during the Cambrian and Ordovician were now caught between the Piedmont and the eastern edge of North America, and subsequently were compressed. This entire compressional episode, like the earlier Grenville orogeny, resulted in thrust faults, folds, felsic intrusions (like the Occoquan Granite of Stop 3), volcanics (like the Chopawamsic Formation of Stop 2), and metamorphism (evident at Stops 2–5). All of this activity was part of a mountain-building episode known as the Taconic orogeny. This was the first phase in the building of the Appalachian Mountains.

We will not visit the Valley and Ridge province on this trip; however we will briefly discuss its geology to complete the story. Further information can be found in Fichter and Diecchio (1993) and in the additional resources listed at the end of this field guide. The results of these events can be seen in sediments deposited west of the Blue Ridge, in the Valley and Ridge province, and in igneous and metamorphic rocks and deformation in the Piedmont. Of note, two additional mountain-building periods, the Acadian orogeny and the Alleghanian orogeny, occurred during the Paleozoic Era. These orogenies are associated with continued collision and the resulting folds, faults, intrusions, and metamorphism as occurred during the earlier Taconic orogeny. While all this mountain-building activity was taking place, sediments were accumulating west of the Blue Ridge, in the Appalachian basin, which developed on the eastern edge of North America in part as a result of loading by thrust sheets and sediment. These sediments were themselves folded and faulted during the orogenies. At the end of the Paleozoic Era, the final result of the full collision of North America and Gondwana was the formation of the Appalachian Mountains on the supercontinent of Pangea.

Pangea existed during most of the Permian and Triassic. During the Triassic, the plates once again began to pull apart. Rifting began to break up Pangea. One system of rifts opened up along the extent of today's east coast, to become the Atlantic Ocean. This rift system included intracontinental rift basins known as the Mesozoic basins. Here in northern Virginia, one such basin is known as the Culpeper basin (Stops 5–7).

As rifting progressed, erosion of the higher land on either side of the Mesozoic basins produced a variety of sediments that accumulated in fluvial, deltaic, and lacustrine environments (Stops 5–7). The rifting also produced mafic igneous intrusions and volcanism (mafic dikes of Stop 3 and diabase sill of Stop 6) in the basins. Locally the igneous rocks are more resistant to erosion; thus as the sedimentary rocks have been eroded many of these igneous rocks, even intrusions formed at depth, are expressed today as topographic highs.

The Mesozoic basins eventually became inactive as the continental margin became passive. However, the Atlantic continued to open along the Mid-Atlantic Ridge and continues even today. During the Mesozoic, sediments also began to be deposited on the new continental margin, continued to be deposited through the Tertiary, and are still being deposited today. These sediments are now part of the Coastal Plain province and the continental shelf. We will see Coastal Plain deposits at Stops 1 and 2.
Acknowledgments

This field guide has been reviewed and improved by Stephen W. Kline of Arkansas Tech University.
References Cited

Aleinikoff, J.N., Horton, J.W., Jr., Drake, A.A., Jr., and Fanning, C.M., 2002, Shrimp and conventional U-Pb ages of Ordovician granites and tonalities in the central Appalachian Piedmont; Implications for Paleozoic tectonic events: American Journal of Science, v. 302, p. 50–75.

Drake, A.A., Jr., Froelich, A.J., Weems, R.E., and Lee, K.Y., 1994, Geologic map of the Manassas quadrangle, Fairfax and Prince William Counties, Virginia: U.S. Geological Survey Geologic Quadrangle Map GQ–1732, scale 1:24,000.

Fichter, L.S., 1993, The geologic evolution of Virginia: National Association of Geology Teachers Short Course, Notebook of Illustrations.

Fichter, L.S., and Diecchio, R.J., 1993, Evidence for the progressive closure of the Proto-Atlantic Ocean in the Valley and Ridge province of northern Virginia and eastern West Virginia: National Association of Geology Teachers, Eastern Section Meeting Field Trip Guidebook, Harrisonburg, Va., p. 27–49.

Kline, S.W., Lyttle, P.T., and Schindler, J.S., 1991, Late Proterozoic sedimentation and tectonics in northern Virginia, in Schultz, Art, and Compton-Gooding, Ellen, eds., Geologic evolution of the Eastern United States, Field Trip Guidebook, NE-SE GSA, 1991: Virginia Museum of Natural History Guidebook 2, p. 263–294.

Lee, K.Y., and Froelich, A.J., 1989, Triassic-Jurassic stratigraphy of the Culpeper and Barboursville basins, Virginia and Maryland: U.S. Geological Survey Professional Paper 1472, 52 p.

Mixon, R.B., Southwick, D.L., and Read, J.C., 1972, Geologic map of the Quantico quadrangle, Prince William and Stafford Counties, Virginia, and Charles County, Maryland: U.S. Geological Survey Geologic Quadrangle Map GQ–1044, scale 1:24,000.

Seiders, V.M., and Mixon, R.B., 1981, Geologic map of the Occoquan quadrangle and part of the Fort Belvoir quadrangle, Prince William and Fairfax Counties, Virginia: U.S. Geological Survey Miscellaneous Investigations Series Map I–1175, scale 1:24,000.

Southworth, Scott, Burton, W.C., Schindler, J.S., and Froelich, A.J., 2000, Digital geologic map of Loudoun County: U.S. Geological Survey Open-File Report 99–150, 1 CD-ROM.
Additional Resources

Cecil, K.K., Whisonant R.C., and Sethi, P.S., 2000, Teacher's guide for the geology of Virginia: Charlottesville, Virginia Division of Mineral Resources, 132 p.

Baedke, S.J., and Fichter, L.S., 1999–2000, The geological evolution of Virginia and the mid-Atlantic region: available online at http://csmres.jmu.edu/geollab/vageol/vahist/

Roberts, Chad, and Bailey, C.M., 1997–2003, The geology of Virginia: available online at http://www.wm.edu/geology/virginia/

Sethi, P.S., Whisonant, R.C., and Cecil, K.K., 1999, Geology of Virginia, CD-ROM 1, Introduction and geologic background: Charlottesville, Virginia Division of Mineral Resources, 1 CD-ROM.

Sethi, P.S., Whisonant, R.C., Cecil, K.K., and Newbill, P.L., 2000, Geology of Virginia, CD-ROM 2, Coastal Plain: Charlottesville, Virginia Division of Mineral Resources, 1 CD-ROM.

Sethi, P.S., Whisonant, R.C., Cecil, K.K., and Newbill, P.L., 2000, Geology of Virginia, CD-ROM 3, Piedmont and Blue Ridge: Charlottesville, Virginia Division of Mineral Resources, 2 CD-ROMs.
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

Joe

Re: Geology Question for Big Ed

Post by Joe » Tue Aug 09, 2011 8:46 am

What amazes me is that they ever figured this out! Geology really is a fantastic science. The only other science that excites me as much is cosmology: the Earth and the Heavens!
Joe

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