Canyon Rim Research Articles

Submarine Sand Dunes and Sedimentary Environments in Oceanographer Canyon

ABSTRACT Observations from research submersibles in the northern part of Oceanographer Canyon reveal the presence of an extensive field of large sand dunes on the canyon floor. The dunes are medium to coarse sand, are oriented across the axis, and the largest of them are as high as 3 m and have wavelengths up to 15 m. Their asymmetry, grain size, and height suggest that they are formed by axial currents flowing up- and downcanyon and that the largest dunes require flows of at least 70 cm/sec. Shelf sand, low in silt and clay content, is transported by currents down and along the canyon walls onto the canyon floor. As the sand enters the canyon, it is mixed with immobile gravel deposits on the canyon rim; lower on the walls, the sand is mixed with silt and clay burrowed by organisms from the se iconsolidated sandy silt that underlies the canyon walls and floor. Upon reaching the canyon floor, the sand is sculpted into bed forms by currents, and the fines are winnowed out and transported out of the canyon. At present, the shelf and canyon walls are being eroded by bottom currents and burrowing organisms, whereas the canyon floor is covered by mobile sand that moves both up and down the axis in this part of the canyon.

Geomorphic effects of a 10‐year storm on a small drainage Basin in the Texas Panhandle

AbstractBedded Permian salt in the Palo Duro Basin of the Texas Panhandle is being considered for isolation of nuclear waste. Studies underway to evaluate the geomorphic processes affecting any waste repository that may be sited in the region include studies of the geomorphic events associated with individual storms. On 26 May, 1978, thunderstorms occurred near Canyon, Texas, which received 130mm of rain, and on a small instrumented watershed at Buffalo Lake, 16 km to the southwest, which received 71 mm of rain. Rainfall at Buffalo Lake was concentrated in a period of 3 hours, representing a return period of approximately 10 years and a maximum 30‐minute intensity of 64 mm/hour.Erosion‐pin fields, topographic surveys, and stakes for headcut monitoring had been established 2 to 3 months before the storm in a 640‐m long tributary canyon to Tierra Blanca Creek downstream of Buffalo Lake. Canyon slopes of moderately to slightly calichified sands and gravels of the Ogallala Formation are capped by well‐indurated caliche on the canyon rim. Erosion‐pin fields showed average net erosion of 2·4 cm (0° to 9° slope) to 2·7 cm (10° to 19° slope) and a single‐pin maximum value of 6·2 cm in the 20° to 29° slope class. Headcuts 1 to 2 m deep in alluvial‐colluvial material on the floor of the canyon migrated as much as 12 m upstream. Canyon floor deposition occurred as a series of elongate bars, 16m long and longer, located at the mouth of tributary gullies, downstream from scours, and at slope breaks. Grain sizes ranged from boulders up to 70cm in intermediate axis deposited in the upper canyon to fine to very fine sand deposited as a sheet up to 25cm thick beyond the mouth of the canyon at Tierra Blanca Creek.In an adjacent canyon a sequence of irregular beds of caliche gravel, mixed sand and gravel, and fine sand up to 3 m thick is exposed. Comparison of this sequence with deposits resulting from the 26 May, 1978, storm suggests that the coarse fraction of the alluvial sequence is deposited by repetitive major storm events. Cobble and boulder units 30 to 70cm thick can evidently be deposited in a few hours. Under the continental climate of the Texas Panhandle, erosion, deposition, and stream incision are taking place primarily in discrete steps related to episodes of intense rainfall.

Effects on the Ecosystem of Sewage Sludge Disposal from a Pipeline

About 57,000 m tons (dry wt) of sewage sludge has been discharged each year for the last 22 years at the brink of a steep-sided submarine canyon in Santa Monica Bay, California. The discharge point is 100 meters deep and 10 km offshore. An area of about 3 sq km of the upper canyon has been substantially changed by the high concentration of sewage solids but the ecosystem is stable. There are fewer species of invertebrates but more species of fish in the canyon; the biomass of both fish and invertebrates is larger than controls. In the region near the canyon rim there are extraordinary populations of clams and molluscs; fishing is far above average for the bay. This solution to sludge disposal causes both negative and positive effects which seem to be about balanced.

SAND MOVEMENT INTO CARMEL SUBMARINE CANYON, CALIFORNIA

Carmel Submarine Canyon heads in shallow water near Monastery Beach at the southeast corner of Carmel Bay, California, U.S.A. Very coarse sand, shaped into large oscillation ripples, covers the narrow shelf between the beach and the canyon; when this sand enters the canyon head, it lies at angles as great as the angle of repose. In some areas, these sand slopes show evidence of active grain flows in the form of downslope-coarsening, inversely graded deposits. The results of a dyed-sand tracer study adjacent to the canyon show that sand moved canyonward during the summer of 1979. Initially the dyed sand, which had been shaped into an oscillation ripple in the center of a 20-m by 60-m grid, moved offshore en ma sse. After a few days, though, the dyed sand dispersed with the center of mass moving canyonward. As wave-transported sand accumulates along the canyon rim, the upper slopes oversteepen, thereby causing some of the sand to avalanche downslope. Systematic changes in sand levels along three lines of rods over 15 months document preferential deposition of sand along the upper slopes; the greatest change occurred at the top of the lines (12-15 m depth) and the least at the bottom (30-40 m). Greater accretion during the spring months than during the summer months probably reflects the more energetic springtime wave climate. Between October 1981 and October 1982, 5.7 m3 of sand was deposited per meter alongslope on the middle line, which gives a calculated depositional rate of approximately 5 00 m /yr in the study area. Although we have monitored this area for over a year, we have not yet documented any large-scale events capable of flushing sand out of the canyon head. The only erosive event we have observed was a small grain flow we generated while digging on the slope.

Formation of Mississippi Canyon: ABSTRACT

The most prominent submarine physiographic trough in the northern Gulf of Mexico is the Mississippi Canyon. This submarine trough has an average width of 5 mi (8 km), length of 75 mi (120 km), and bathymetric relief of 985 ft (300 m). Its origin has generally been attributed to channel entrenchment of the Mississippi River during lowstands of sea level and erosion of the more distal parts by turbidity currents or submarine gravity flows. In the last 2 years, a dense, high-resolution seismic and side-scan sonar grid 1,000 ft (305 m), together with deep borings utilized to obtain samples for carbon-14 dating, has been used to establish a time-stratigraphic framework and origin for this feature. Nine horizons, chosen from borings and dated by carbon-14 and paleontologic meth ds, have been traced laterally on the seismic lines. These horizons range in age from Illinoian (~ 400,000 years B.P.) to late Holocene (3,500 years B.P.). During the interval from Illinoian to late Pleistocene (25,000 to 27,000 years B.P.), the Mississippi River deposited a series of fluvial and deltaic deposits of approximately 3,300 ft (1,000 m). There is no evidence that a submarine canyon existed in the vicinity of the present feature during this time interval. Approximately 25,000 years ago, a carbon-14-dated horizon was truncated by the initial formation of the submarine canyon. Samples dated by carbon-14, obtained near the base of the canyon fill, show that by 20,000 years B.P., canyon fill had commenced. Thus, this major submarine trough had, at most, End_Page 1427------------------------------ 7,000 years in which to remove 1,500 to 2,000 km3 of material. It is highly probable, therefore, that the canyon originated from massive shelf-edge slope failure on an unstable continental margin. A series of successive failures, each one creating an upslope instability that triggered the next failure, caused an elongate trough to form that excavated the canyon to a depth of 4,000 ft (1,220 m) below present sea level. Once the canyon had formed, its steep side walls continued to be unstable, and sediments slumped into the canyon axis, forming the initial canyon fill. This phase is well documented: the lowermost sediment fill is composed of displaced material similar to that now found on the canyon rim. Large scars from sidewall failures can also be easily mapped on the seismic data. From 20,000 years to approximately 5,000 years B.P., a series of late Wisconsin and Holocene delta lobes formed, which were responsible for the remainder of the fill of the canyon. During the past 5,000 years only a thin deep-water pelagic drape has been deposited within the canyon. Maps have been constructed that depict the various horizons, and the geometry of these horizons verify this mode of formation. End_of_Article - Last_Page 1428------------

Pennsylvanian and Early Permian Paleogeography, Southern Colorado Plateau and Vicinity: ABSTRACT

Abstract Pennsylvanian and Lower Permian sedimentary rocks of the southern Colorado Plateau have been the subject of much controversy concerning their correlation and origin. Correlation of rock sequences and major unconformities from the fossiliferous basins onto the adjacent shelves, where relatively unfossiliferous rocks were deposited, has provided a new interpretation in terms of regional stratigraphy and depositional analysis. The Supai Group was deposited in the Grand Canyon Embayment adjacent to the Cordilleran Geosyncline. Sediments of Morrowan, Atokan, Virgilian and Wolfcampian ages were deposited in a variety of offshore marine and shoreline environments. A persistent southwest-to-northeast-trending unstable area, herein named the Sedona Arch, confined all Supai sediments, except Virgilian, to the Grand Canyon and western Mogollon Rim regions; the other strata are truncated beneath the sub-Virgilian unconformity or undergo significant facies change across the arch. The Naco Group of Desmoinesian, Missourian, and Virgilian age was deposited on the Mogollon Shelf adjacent to the Pedregosa Basin. Except for Virgilian strata, these dominantly marine rocks are also truncated beneath the sub-Virgilian unconformity across the Sedona Arch. Thus the bulk of Supai and Naco rocks are not as closely related as most previous workers had thought. Mostly marine rocks of the Molas Formation and Hermosa Group were deposited in the Paradox Basin. The northwest-to-southeast-trending Kaibab Arch provided the barrier between these rocks and the Supai and Naco to the south. Except for several transitional units, the Supai, Naco, and Hermosa Groups were deposited in distinctly separate basins and the units do not generally intertongue. The Wolfcampian Esplanade and Cedar Mesa Sandstones and Halgaito Formation form a distinct eastward-thinning wedge of rocks west of the Sedona Arch. These high-energy marine shoreline and supratidal units grade westward into thick marine carbonate sequences of the Cordilleran Geosyncline. A widespread redbed sequence comprising the Hermit and Organ Rock Formations was deposited across the entire study area. The continental and possibly tidal deposits represent a sharp change in depositional regime from the underlying and overlying sandstone deposits. The youngest sequence of deposition studied consists of sandstone, redbed, evaporite, and carbonate rocks of the Schnebly Hill Formation and DeChelly Sandstone. These units are centered around the Holbrook Basin and represent a complex of shallow marine, high- and low-energy shoreline, eolian, and sabkha depositional environments. This depositional sequence was confined to an area east of Grand Canyon and south of the San Juan River by the Sedona and Kaibab Arches. Both formations grade upward or intertongue with the overlying Coconino Sandstone and related rocks.

Recent Landslides in Salmon Creek Canyon, Idaho

Previous articleNext article No AccessRecent Landslides in Salmon Creek Canyon, IdahoCharles A. LeeCharles A. Lee Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 46, Number 4May - Jun., 1938 Article DOIhttps://doi.org/10.1086/624667 Views: 3Total views on this site Citations: 5Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Lawrence Rosenthal Eyewitness Identification and the Problematics of Blackstonian Reform of the Criminal Law, SSRN Electronic Journal (Jan 2019).https://doi.org/10.2139/ssrn.3362968Marius Necsoiu, Ronald N. McGinnis, Donald M. Hooper New insights on the Salmon Falls Creek Canyon landslide complex based on geomorphological analysis and multitemporal satellite InSAR techniques, Landslides 11, no.66 (Oct 2014): 1141–1153.https://doi.org/10.1007/s10346-014-0523-8David R. Streutker, Nancy F. Glenn, Rupesh Shrestha A Slope-based Method for Matching Elevation Surfaces, Photogrammetric Engineering & Remote Sensing 77, no.77 (Jul 2011): 743–750.https://doi.org/10.14358/PERS.77.7.743Nancy F. Glenn, David R. Streutker, D. John Chadwick, Glenn D. Thackray, Stephen J. Dorsch Analysis of LiDAR-derived topographic information for characterizing and differentiating landslide morphology and activity, Geomorphology 73, no.1-21-2 (Jan 2006): 131–148.https://doi.org/10.1016/j.geomorph.2005.07.006John Chadwick, Stephen Dorsch, Nancy Glenn, Glenn Thackray, Karen Shilling Application of multi-temporal high-resolution imagery and GPS in a study of the motion of a canyon rim landslide, ISPRS Journal of Photogrammetry and Remote Sensing 59, no.44 (Jun 2005): 212–221.https://doi.org/10.1016/j.isprsjprs.2005.02.001