Join Dr. Alley and his team as they take you on "virtual tours" of National Parks and other locations that illustrate some of the key ideas and concepts being covered in Unit 6.
TECH NOTE - Click on the first thumbnail below to begin the slideshow. To proceed to the next image, move the mouse over the picture until the "next" and "previous" buttons appear ON the image or simply use the arrow keys. Virtual Fieldtrip #1: Canyonlands
Canyonlands to the Grand Canyon
Rivers Roll Rocks, and Dams Get in the Way. All photos by R. Alley from the Penn State CAUSE trip, 2004
Canyonlands, near Moab, Utah, preserves the junction of the Colorado and Green Rivers. The rocks are mostly from the Mesozoic (a couple of hundred million years ago) and include sandstones and shales.
Sunrise washes the red rocks of Canyonlands in the Needles area, one of several distinct districts of the park--the rivers are not bridged, so getting from one district to another can take a lot of driving.
Sunrise over sleeping bag, Needles area group campground, Canyonlands.
Sunrise over sleeping students, Needles area group campground, Canyonlands.
A field of mallows, entrance to Needles area, Canyonlands.
A desert milkweed, Canyonlands National Park
Rock features, Canyonlands. The sandstones shown here have weathered into fantastic patterns.
The Colorado River and Canyonlands, as viewed from Dead Horse Point State Park. Notice the muddy water, the sand bars in the river, and the tree-covered sand bars along the river. This clearly is a river that moves much sediment.
The Glen Canyon dam, and highway bridge, viewed from a raft trip on the Colorado River below the dam. Lake Powell, on the other side of the dam, catches the sediment from the river, so that clean water is released from the dam.
Stephanie Shepherd and Topher Yorks filming at the bottom of the Grand Canyon. Notice that the water behind them is nearly free of sediment, so you can see the bottom clearly in the closer parts.
The Colorado River below the Glen Canyon Dam. The cliffs are still spectacular, but the sandbar across the center (arrowed) has largely been eroded away by the sediment-free waters released from the dam.
Bottom of the Grand Canyon, from the Silver Bridge that takes the Bright Angel Trail across the river. The water is clear. The left foreground shows a boulder bar, not a sand bar--much of the sand has been washed out of the Canyon by the clean water released from the dam upstream.
Virtual Fieldtrip #2: Mississippi Delta National Wildlife Refuge
Deltas, rivers and floods: living with the moving water. This picture shows the Mississippi River Delta, south of New Orleans. Plants are green, deep water is blue, and the grayish-white is mud carried by the river. A few poofy white clouds are also visible. Source:
Delta in Mudder Bugt ('Muddy Bay'), east Greenland. A stream flowing from the bottom of the picture has deposited the delta into the fjord at the top of the picture. Sediment supply is slow enough to allow waves in the fjord to rework the sediment to make the beaches that outline the delta. Helicopter skid is visible in the far lower left.
A delta near the one in the previous picture. The stream, flowing from the lower left, is braided, and the pattern of sand bars and beaches is quite interesting. This is Greenland, so the objects offshore are icebergs rather than oil tankers or merchant ships.
Another Greenlandic delta, close to those in the two previous pictures. Some of the bars in the braided river supplying the delta have been stable long enough for tundra vegetation to become established.
Two more deltas, Tasermiut Fjord, South Greenland. Careful examination will show that the deltas are higher on the right, where the streams enter, and lower on the left--sediment builds up as well as out.
Meandering stream feeding Sondresermilik Fjord, South Greenland. Streams flow fastest on the outside of a curve, eroding the curve, until a shortcut forms and leaves an oxbow lake (pink arrow). Low natural levees (white arrow) separate the oxbow lake from the stream.
http://water.usgs.gov/nwsum/WSP2425/images/levee.jpeg, US Fish and Wildlife Service photo, from Effects of the Great Midwest Flood of 1993 on Wetlands, by James R. Kolva, U.S. Geological Survey. This Missouri levee failed during 1993 flooding in the Mississippi Basin. Many (but not all) artificial levees rest on much smaller natural levees.
http://www.mvd.usace.army.mil/hurricane/chr.php Miscellaneous Photos coe_6, US Army Corps of Engineers. Flooding from Hurricane Katrina, New Orleans, 2005. The levees held on the waterway shown here; the floodwaters outside came through a different levee, and are actually lower than the water between the levees seen here.
http://www.mvd.usace.army.mil/hurricane/chr.php Miscellaneous Photos coe_17, US Army Corps of Engineers. Flooding from Hurricane Katrina, New Orleans, 2005. A very waterlogged Wendy<92>s outlet is visible in the left center. The muddiness of the water is also evident.
http://www.mvd.usace.army.mil/hurricane/chr.php Miscellaneous Photos coe_20, US Army Corps of Engineers. Flooding from Hurricane Katrina, New Orleans, 2005. The colors on the water indicate an oil slick. The floodwaters raced through houses, gas stations, repair shops, chemical plants and more, releasing many toxic chemicals.
Orange indicates land loss from the Mississippi Delta between 1956 and 1978, red is loss 1978-1990, yellow shows gain 1956-78 and green shows gain 1978-1990. Losses dominate, although sedimentation has been lengthening the <93>log flume<94> of the main shipping channel extending to the southwest (lower left). Loss slowed after 1978 because most of the land was already gone. Source:
Virtual Fieldtrip #3: Bayou, Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
Many trees in wetlands grow 'knees', projections sticking up from the roots, that help stabilize the trees and may help the tree roots <93>breathe<94> when they are underwater. You can see such knees on the cypress trees in the bayous of Barataria Preserve, in Jean Lafitte National Historical Park and Preserve on the Mississipp i Delta in Louisiana, a great place to see lots of things growing. All pictures in this slide show are by R. Alley unless otherwise indicated.
Of course there are alligators in the bayou! Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
Taken from an airboat (you can see the boat in the bottom of the picture), Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana. There is water under the plants straight ahead, and that is where we went.
This frog was sitting on my knee after we air-boated through a particularly dense patch of plants. Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
Palmetto. Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
Dragonfly on palmetto, Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
White spider lily, Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana.
Richard Alley's boot in water, Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana. Notice the oily 'scum' floating on the water to the upper right of the boot. A place such as this bayou grows LOTS of plants, which die and sink. In the mud, oxygen is scarce. The decaying plants are not 'burned' efficiently in the low-oxygen environment, and some of the formerly living material produces oil. Oil mostly comes from dead algae, coal from dead woody material, and natural gas (methane) from both. Most of the oil and gas float up and escape to the surface, as seen here. In some times and places, some of the oil and gas are trapped in mud. We humans are spend ing a few hundred years using the oil, gas and coal that have been saved up by nature over a few hundred MILLION years, so we're using them about a million times faster than nature saved them.
Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana. Notice the bubbles in the bayou. These are 'swamp gas,' which is methane, and is also called natural gas. As described with the previous picture, the gas that is made naturally and doesn't escape is what is now being 'fracked' from shales under P ennsylvania and other states.
Virtual Fieldtrip #4: Mammoth Cave
Mammoth Cave: A World Unknown to Daytime--That May Matter to Your Drinking Water.
Waterfall into historical entrance of Mammoth Cave. National Park Service Photo. All pictures in this slide show are by R. Alley unless otherwise indicated (as for this one).
Many cave creatures are uniquely adapted to their environment, which may seem strange to us but is normal to them. National Park Photo
Here, a cave cricket sits on a limestone ledge in Mammoth Cave. (From tip of front leg to tip of back leg, the cricket is about 3 inches long.)
http://photo.itc.nps.gov/storage/images/maca/BROADWAY.JPG National Park Service Photo. Broadway of Mammoth Cave is one of the many huge passageways dissolved in the layered limestone of the park. Roof collapses happen occasionally, as shown by the rubble on the right, but are rare, so tourists are considered safe.
Cindy Alley (who prepared many of the graphics for the course) and friend Sue Croll in Mammoth Cave. The cave is immense; this room is several stories high.
Gypsum flowers, Mammoth Cave (photo about 6 inches across). Limestone (calcium carbonate) often has a little gypsum (calcium sulfate), which makes formations with this distinctive appearance.
Channels in limestone, Mammoth Cave (photo about 2 feet across), produced by dissolution of limestone in acidic groundwater.
Passage in Mammoth Cave. This probably started as a vertical crack, which was widened by dissolution of the limestone rock into acidic groundwaters flowing along the crack.
Frozen Niagara section of Mammoth Cave. More groundwater enters this region than in the rest of the cave, because the sandstone “lid” that covers much of the cave is broken here. The water picks up extra carbon dioxide in soil, dissolves limestone, then loses the extra carbon dioxide to the cave air (which exchanges rapidly enough with the outside to exhaust the carbon dioxide), and deposits the dissolved limestone as cave formations.
Water often enters along cracks; a line of hollow stalactites (“soda straws”) is arrowed in the upper left. The greenish color just below that line comes from algae growing where a Park Service light provides a little energy.
Mammoth is not alone among Park Service Caves. This is Carlsbad Caverns. Wind Cave, Jewel Cave, and others are equally beautiful.
The sandstone cap that prevents collapse of Mammoth and allows the cave’s immense length does reduce drip-water entry and thus cave formations, so other Park Service caves are often prettier than Mammoth. This roughly 20-foot-high feature is in Carlsbad Caverns.
bymap/gastropod&operculae.htm USGS Photo Fossil snails (gastropods) in limestone, Cades Cove, Great Smoky Mountains National Park. Most caves and sinkholes are in limestone, and most limestone started out as shells or skeletons of marine creatures. Many shells are so broken as to be unrecognizable, but quite pretty fossils can be found.
Soil on limestone bedrock in excavation for a basement, State College, PA. The rock layers slope down to the lower right, and are curved a little. Dissolution has enlarged cracks and deepened some places more than others. When the deeper places become big enough, we say a sinkhole has formed.
Another view of State College, PA soil over limestone, revealed in an excavation for a basement. A small sinkhole has formed to the right, where the redder soil dips down past the whiter stone.
http://va.water.usgs.gov/karst_img/karst_photo2.htm USGS Photo. Sinkhole near Shenandoah National Park. The center of the hole is just to the right of the right-most person. The ground slopes into the hole from all directions, so rainwater that runs in and does not evaporate must go downward through the bottom of the hole.
Sinkhole in limestone, Cades Cove, Great Smoky Mountains National Park. The sinkhole is the dip containing tree trunks in the foreground. Sinkholes most commonly form by dissolution of limestone along joint intersections, but cave-roof collapse also may form sinkholes. Here, tree trunks have fallen in, but in many places people have dumped things in, which go right to the groundwater.
cadesCove/GISData/bymap/sinkholes.htm USGS photo Sinkholes in limestone near Gregory’s Cave, Cades Cove, Great Smoky Mountains National Park. Similar scenes are common along the Appalachians in many places. Soil, rocks, leaves, etc., fall into such holes, yet the holes are not full, indicating that materials are sinking toward the groundwater.