assign9

Geography 110H

Assignment on tectonics and landscapes

This week we are discussing aspects of global tectonics and the relationship between landscape and tectonic processes. The notes for this week primarily concern topics covered in chapters 11 and 12, and I am particularly recommending that you read one or two web documents, most notably the USGS document entitled "This Dynamic Planet", which gives an excellent overview of virtually the entire range of topics covered in those two chapters.

Because we have so little time, there is no way we can explore all of the ramifications of this material. What I would like to do for the assignment this week is to have each of you work on one small piece of landscape, and to try to fit it into the broader context.

Each of you will be assigned one location or region. In some cases this will be tied to a specific geologic event, in other cases it won't. Your job will be to investigate that location or region and to answer a series of fairly general questions. If it's hard to find answers to all of these, feel free to adapt your approach to fit the information that is available, but this at least gives you a framework for thinking about what to do.

Here are the questions:

1. Where is this region or location?

Looking at the regional picture, try to describe the visible characteristics that set it apart from adjacent regions; in other words, try reading the grain of the landscape and see whether what you see in the image is consistent with what you are able to learn about it from other sources. Would you be able to identify the boundaries of your region just by looking closely at the map? You can also consult online shaded relief images; here are a couple of links that will allow you to look at these without coming into the lab:

for the global context: World View with Crustal Plate Boundaries

for the U.S., try either of these:
Color Landform Atlas of the United States
Relief Maps of the United States

If you aren't sure about what terminology to use, don't worry. Describe what you see as best you can. I will leave the large poster showing the radar image of the conterminous U.S. on display in SS001.

2. Look up any sources you can find to give you the regional geologic setting. For most of these, there will be a part of the story that can be explained by reference to plate tectonics. In any case, a brief overview of the geologic background should be available. Questions that can be answered might include, for example: what are the major types of bedrock, what are the dominant types of geologic structures, what is the general geologic history of evolution of this landscape (i.e. why does it look the way it does today), what are the underlying causes of any recent geologic events associated with this region?

To find sources, you may use sites from some of the linked documents accessible from the list below.

You may try an Uncover search, but I have already tried this out to save you some time, and I can tell you that (1) a lot of the articles will be much more specialized than you can use, and (2) a lot of the journals aren't in our library. We do have journals like Geological Society of America Bulletin and Geology, so if you find citations from those, or from others like Science and Nature, they may be worth a trip to the stacks. But don't waste a lot of time looking.

You can also look in the electronic library catalogue. Some of the places on the list have had books published about them within the last 10-20 years. Bear in mind that our understanding of plate tectonics before the mid-70's was pretty primitive, and therefore some good regional physiography and geomorphology books that predate that time will be lacking important information. Don't avoid using them, but try to find something more current. I am aware that this can be time-consuming; I don't expect a long report, so don't kill yourself searching. Before you go to the library, decide what you are looking for and don't go beyond that.

Another possible source would be general introductory geology textbooks and regional geology textbooks. . There are also some possible sources in the library collection. There's a book by Charles Hunt from 1974 called "Natural Regions of the United States and Canada" (I have a copy, which I will leave in SS001) and there's a book on the geologic story of the National Parks ( haven't actually looked at that one, though).

3. Try to reconcile what you learn from your sources with what you see on the map and what you have learned overall about plate tectonics and geologic structure from the text. Again, I am not looking for something that is technically very sophisticated. I'm really just interested in your taking a look at one piece of landscape and trying to figure out whether you can make sense of it in the context of what you are learning. It may be that some of what you look at is just too complicated; that's ok, describe what you can understand and just indicate where you get lost. There are a lot of geologic features that the professionals still haven't figured out, and sometimes the technical language obscures the fact that we just don't have a good explanation. The Rocky Mountains are a good case in point: I have yet to see a decent explanation that is intuitively as clear as the explanations of other mountain ranges like the Appalachians.

Here's a list of possible topics. If you have an idea for something else that's not on this list, just let me know. Please check with each other to avoid duplicating the choice of topics.

The 1994 Northridge earthquake
The Colorado Plateau and the Grand Canyon
The Sierra Nevada mountains, which can also be related to the Great Valley and the Coast Ranges of California
Death Valley and environs
New Madrid seismic zone and the earthquakes of 1811-1812
The Snake River Plain and the Yellowstone hot spot
The Chesapeake Bay bolide (meteorite impact)
The Appalachian Mountains, including major physiographic provinces and geologic evolution
Mount St. Helens and the Cascades
The Wasatch Fault and the Great Basin of Utah
The Black Hills (South Dakota)
The San Rafael Swell (Utah)
The Rio Grande rift
The Columbia Plateau basalts (although this is closely related to the Snake River Plain story)
The Loma Prieta earthquake, or the San Andreas fault (although both are related at least in part to the Northridge earthquake story)
Great earthquakes in the Pacific Northwest

or, if you're particularly intrigued, you can try the Himalayas or Iceland (particularly the Vatnajokull eruption from l996), even though these are outside of the continental U.S. Same goes for the earthquake in Kobe, Japan from a couple of years back, or the eruption of Mt. Pinatubo in 1991, or the East African rift valley - Afar triangle - Red Sea area.

Here are some general links:

links related to geologic structures
(Note that the site "Geomorphology from Space" on this list has a lot of other places besides those I've included)

And just in case you're interested,
A Geologist's Lifetime Field List
American Geophysical Union - Science and Society
Plate tectonics and the evolution of climate
Viewing the Morphology of the Mid-Atlantic Ridge From a New Perspective

Global tectonic and volcanic activity of the last one million years
Global Earth History
Tour of National Parks geology

Colorado Plateau and Grand Canyon

Volcanoes of the Pacific Northwest

Basin and Range

Death Valley

Sierra Nevada Mountains and general geology of California

Earthquakes and faults in southern California

Snake River Plain and Yellowstone

Geology of the Rocky Mountains

Chesapeake Bay bolide

Appalachian Mountains

Crater Lake

Black Hills

New Madrid seismic zone

The Channeled Scablands of eastern Washington

Himalayas

Some other volcanoes...