Canyon Passage Fix
These passages are formed by underground streams that follow the slightly tilted layers of limestone, eroding channels downward through the bedrock. These passages are usually taller than they are wide, and resemble canyons you might explore above ground, except that they have a cave ceiling over top!
Large Canyon Composite cave passages form from several passages eroding together. They can be formed from the ceiling or floor of stacked tube passages breaking down and joining together to form a larger open passage with additional canyon components. Many of the upper tour routes in Mammoth Cave follow these large canyon composite cave passages.
A keyhole passage has a shape like its name suggests: It has an oval top and then has a narrow passage extending down vertically from the oval. These passages are really just a combination of a tube passage and a canyon passage. They can tell you about changing water levels that occurred as the cave was forming. The tube at the top forms at or just below the water table, but when the water table lowers, the stream that was in the tube cuts a canyon in the floor as it goes down toward the new water level. Fat Man's Misery on the Historic Tour is an excellent example of a keyhole passage.
Allow fish passage into Cochran Creek to help sustain populations of coho, steelhead, and coastal cutthroat trout, while enhancing and expanding productive tidal, brackish, freshwater, and riparian...
Recover Klamath River salmonid populations by removing 4 dams on the Klamath River (Iron Gate, Copco 1, Copco 2, and JC Boyle) and opening up fish passage to over 400 miles of potential spawning and...
Ensure long-term passage for juvenile and adult steelhead in San Francisquito Creek beyond Searsville Dam on San Francisquito Creek by working with Stanford University, resource agency, non-profit,...
Transportation corridors such as highways confine stream channels and increase sedimentation, pollution, and habitat degradation from storm runoff and altered streamflows. Culverts and other passage or drainage modifications associated with roads often block migration and restrict fish movements, which can fragment populations.
The submarine Mona Canyon is a rift between Puerto Rico and Hispaniola of the Greater Antilles. An integrated marine geophysical data set, including multibeam bathymetry, side-scan sonar imagery, single channel and multichannel seismic reflection profiles is used to evaluate the morphology, structure, and tectonic evolution of the Mona Canyon. A structural restoration of the central Mona canyon indicates that extension in the rift initiated in the Middle Oligocene, approximately 30 Ma. A minimum total extension of 6.1 km and a minimum longitudinal strain of 11.4% across the central Mona canyon are calculated. The overall extension is proposed to have occurred over two phases. Phase I occurred from the Middle Oligocene to Late Miocene, and was a slow (0.09 mm/yr) stage of at least 1.7 km of opening. Phase II was most likely controlled by the impact of the subducted southeast portion of the Bahamas platform beneath the northeastern Caribbean plate margin. Phase II was a more rapid (0.4 mm/yr) stage of extension of at least 4.4 km that occurred from the Late Pliocene to the Recent as the SE Bahamas collision warped the middle and upper slope of the northern Puerto Rico margin along its advancing path and slowed the eastward movement of Hispaniola relative to Puerto Rico. The upper reaches of the Mona canyon form the trailing edge of the Puerto Rico-Virgin Islands block as it pulls away from a pinned Hispaniola. The Mona reentrant marks the trailing edge of a northern Hispaniola forearc sliver that forms due to increased coupling between the subducting North America plate and the overriding plate.
While sediment density flows (i.e., turbidity currents) are the most significant mechanism for depositing thick sand-rich beds in deep-water environments, rarely can beds be linked to specific flows with measured properties. Yet, this was achieved in a recently completed study that documented the passage of 15 flows along the axis of Monterey Canyon, offshore California using multiple sensors over an 18-month period. The flows were recorded by six downward looking acoustic Doppler current profilers (ADCP) moored between 285 and 1850 meters water depth (mwd) and upward looking ADCPs on a seabed frame in 1830 mwd. These flows had propagation velocities up to 7.2 m/sec, the fastest yet recorded by instruments. Heavy (800 kg) objects were carried for kilometers and left entombed in meters-thick sediment cover. Three of the flows ran for >50 km and continued past the deepest sensor (1,850 mwd). Repeated seafloor mapping and sediment coring documented the impact of these flows on the canyon floor morphology and deposits. During the experiment the canyon floor was mapped with multibeam sonars 6 times between 190-540 mwd and 1500-1900 mwd using Autonomous Underwater Vehicles (AUV) at 1-m lateral grid resolution and 4 times using a Remotely Operated Vehicle (ROV) at 5-cm lateral grid resolution in 1830-1840 mwd. The shallower AUV surveys (190 to 540 mwd) revealed flow-associated 3 m bathymetric changes, interpreted as migrations of crescent shaped bedforms along the canyon axis. Below 1500 mwd the bathymetric changes are more-subtle. Bathymetric differences between surveys bracketing the largest flow (January 15th, 2016) show up to 87 cm of net deposition and up to 39 cm of net erosion where the slowing flow passed over the upward looking ADCPs at a velocity of approximately 3.3 m/s. To characterize the deposits left by this flow and to track its runout, 40 ROV-collected vibracores (
Earlier this week, the blaze shut down a 10-mile stretch of California 140, where fire raged up tufts of dry grass on the canyon side, spitting out gray smoke that spilled into Yo sem ite, obscuring its vertical vistas.
In south-central Montana, meanwhile, a 9-square-mile blaze skirted a line of flame retardant intended to shield a ski area outside the resort town of Red Lodge. The fire pushed down the canyon to within about a mile and a half of the top of the ski hill, said Jeff Gildehaus with the Custer National Forest.
The Antelope Valley Area near Page, Arizona (Slot Canyons) has become one of the most photographed areas of the Western United States since it was first discovered by photographers in the 1970's. Known for its colorful Navajo sandstone walls, narrow passages that almost remind you more of a cave than a canyon, they were created by water flowing through narrow creeks for millions of years down to Lake Powell. All of the well known landscape photographers have images in their portfolio from this area. Today, the most visited of the slot canyons, Upper Antelope Canyon also known as Corkscrew Canyon has gotten well known, partly because it is easily accessible and the most publicized, and has become a major tourist attraction. Once a must photograph place for the photographer, now tourists of every type descend on the Canyon making the act of getting a good photograph much more difficult. Since these canyons are on Navaho Land, you must have a Navaho guide but in many cases the right to lead tours is leased out to private companies that may or may not hire Native Americans as guides. Upper Antelope Canyon is the most well known and at least 4 of the tour companies that line Lake Powell Blvd., the main street of Page, can take you out to the Canyon, or you can drive out Highway 98, milepost 299, to the parking area and get a ride out to the canyon with a guide. Either way the cost is the same. This canyon is an easy walk, you get out of the truck and walk through sand into the canyon and the passage is flat. During the peak season 600-800 people a day visit Upper Antelope and this may be increasing.
You can select from a regular tour that runs about 11/2 hours; it moves rather fast and is really designed for the tourist. They also have photographic tours that limit the number of people, give you about 2 hours in the canyon and are designed to point out the main photogenic details and allow time to photograph. While at one time the photographic tours really gave you an advantage, the sheer numbers of people that pass through the canyon has reduced this advantage. While the tours are all carefully timed and the tour leaders of the photographic tours will stop the regular tours to let you get your shot, you are still rather rushed to get an image and you are always expecting someone to come around the corner just as you create your exposure. While you can still get great images, don't expect a lot of solitude or a lot of time to compose and "experience" the moment.
Devil's Elbows Canyon was a Z-shaped passage divided between Fafnir's Crest and Tundra-Vald, where it opened at the south end. Choke was the canyon's lowest point. (PROSE: Strangers in the Outland)
Congressman Ben Ray Luján (D-N.M.), the U.S. House Assistant Speaker, along with U.S. Senators Tom Udall (D-N.M.) and Martin Heinrich (D-N.M.) and U.S. Representatives Deb Haaland (D-N.M.) and Xochitl Torres Small (D-N.M.), applauded the House passage of an amendment to protect the integrity of the Chaco Canyon region. Introduced by Congressman Luján, the amendment establishes a one-year moratorium on oil and gas drilling on federal lands near the Chaco Culture National Historical Park.
"The All Pueblo Council of Governors celebrates passage of this important legislation by the U.S. House of Representatives. Without the tireless work of the New Mexico congressional delegation we would not be where we are today in protecting critical areas within the sacred landscape of the Greater Chaco Region. Assistant Speaker Lujan, with strong support from Congresswoman Haaland and Congresswoman Torres-Small, led the effort in the House on this measure. A similar effort is being undertaken in the Senate FY 2021 Interior appropriations bill by Senator Udall, the ranking member of the Senate Interior Appropriations Committee, with the strong support of Senator Heinrich. We are hopeful that the Senate effort will be as successful as the House effort and this important protection for Chaco will soon become law," said Chairman J. Michael Chavarria, All Pueblo Council of Governors. 041b061a72