Geology Commons^™

"Pit Craters", Lava Tubes, And Open Vertical Volcanic Conduits In Hawaii: A Problem In Terminology, William R. Halliday

International Journal of Speleology

Almost from the 1849 publication of the term pit crater, volcanologists have disagreed about the parameters differentiating these features from other vertical volcanic structures. Kaluaiki is a jameo giving entry to Thurston Lava Tube in Hawaii Volcanoes National Park. Long-standing misidentification of it as a pit crater is an example of misunderstandings arising from the lack of a clear definition of pit crater. In general, pit craters are unrelated to lava tube caves genetically, but two special cases are discussed. One probably is genetically related to a rift tube deep below the surface; the other is a complex of a …

The Origin Of Tubular Lava Stalactites And Other Related Forms, Kevin Allred, Carlene Allred

International Journal of Speleology

Tubular lava stalactites are often found in lava tubes. Field observations, sample analysis, and comparative studies indicate that these are segregations extruded during cooling from partially crystallized lava al about 1,070 - 1,000 °C. Retrograde boiling (gas pressure) within the lava provides a mechanism to expel the interstitial liquid. In addition to tubular lava stalactites, a variety of other lava features can also result, such as lava helictites, lava coralloids, barnacle-like stretched lava, runners, runner channels, and some lava blisters and squeeze-ups.

Lava Tube Remelt By Radiant Heat And Burning Gasses, Kevin Allred

International Journal of Speleology

Some volcanologists assume that interior surfaces of hot lava tubes can commonly be remelted by burning gases and radiant heat. Pending further data, this appears to be unlikely.

Overview Of The 8th International Symposium On Vulcanospeleology, William R. Halliday

International Journal of Speleology

In February 1998 the 8h International Symposium on Vulcanospeleology was hosted by CEGEA (Cave Exploration Group of East Africa) in Nairobi, Kenya: it was attended by 16 scientists coming from 4 continents. Pre- and Post- Symposium excursions allowed the participants to have an overview on the most important and famous volcanic cave of that area.

Lava Caves Of The Republic Of Mauritius, Indian Ocean, Gregory J. Middleton

International Journal of Speleology

In their Underground Atlas, MIDDLETON & WALTHAM (1986) dismissed Mauritius as: “very old volcanic islands with no speleological interest”. Recent investigations indicate this judgement is inaccurate; there are over 50 significant caves, including lava tube caves up to 687 m long (one 665 m long was surveyed as early as 1769) and 35 m wide. Plaine des Roches contains the most extensive system of lava tube caves with underground drainage rising at the seashore. Notable fauna includes an insectivorous bat and a cave swiftlet (Collocalia francica), the nests of which are unfortunately prized for ‘soup”. The caves …

"Hades" - A Remarkable Cave On Oldoinyo Lengai In The East African Rift Valley, Gordon J. Davies

International Journal of Speleology

Oldoinyo Lengai is the world’s only active carbonatite volcano, situated in northern Tanzania within the Eastern Rift Valley, al 2.751 degrees S, 35.902 degrees E. It forms an isolated symmetrical cone at the southern end of Lake Natron, with a summit elevation of 2,890 m (9,480 ft). Periodic eruptions of ash and lava have been recorded since about 1880, and with increasing precision during this century since 1904. In 1990 a routine expedition to monitor activity levels at the summit led to the discovery of a remarkable cave located in the crater floor, filled with numerous long delicate pale yellow …

A Preliminary Assessment Of Wave, Current, And Sediment Interactions On The Louisiana Shoreface Adjacent To The Isles Dernieres, David A. Pepper, Gregory W. Stone, Ping Wang

Geology Faculty Publications

The Louisiana coast is generally characterized as a low wave-energy environment where sediment transport is dominated by the influence of the Mississippi and the Atchafalaya Rivers. Winter cold fronts, however, generate waves and currents that have a significant impact on a variety of Louisiana’s coastal environments, although field data regarding their influence on the inner shelf are extremely sparse. During a 12-d period that included the passage of two cold fronts, waves and near-bed currents were measured on the Louisiana inner-shelf (depth-8 m) using a sophisticated bottom-mounted instrumentation system. Bottom boundary layer parameters were then calculated using wave-current interaction models, …

Effective Elastic Thickness Of The Lithosphere Along The Easter Seamount Chain, Sarah E. Kruse, Zhengro J. Liu, David F. Naar, Robert A. Duncan

Geology Faculty Publications

Bathymetry and gravity data collected during Legs 5, 6, and 7 of the 1993 GLORIA Expedition and the recently released 2-min altimetry-derived global gravity grid are used to determine the effective elastic thickness of the lithosphere along the Easter Seamount Chain (ESC). Forward modeling, admittance, and coherence methods yield consistent results. With the exception of the eastern and western ends of the ESC the effective elastic thickness along the chain is ∼1–4 km. The thin elastic thickness for the majority of the ESC seamounts is compatible with a young seafloor age at the time of loading derived from new radiometric …

Characteristics Of Street Sweepings In Florida Cities, Robert Brinkmann, Jeffrey G. Ryan, Mark Billus

Geology Faculty Publications

No abstract provided.

Distribution Patterns And Accumulation Rates Of Fine-Grained Sediments In Upper Tampa Bay, Florida, Gregg R. Brooks

Reports

Tampa Bay, a drowned river valley, is the largest estuary on Florida's west coast.

Surface sediments consist of a mixture of carbonate and terrigenous clastic sands and muds.

The objectives of this study are to determine accumulation rates and processes controlling the distribution patterns of fine grain sediments.

Transient Electromagnetic Sounding For Groundwater, David V. Fitterman, Mark T. Stewart

Geology Faculty Publications

The feasibility of using the transient electromagnetic sounding (TS or TDEM) method for groundwater exploration can be studied by means of numerical models. As examples of its applicability to groundwater exploration, we study four groundwater exploration problems: (1) mapping of alluvial fill and gravel zones over bedrock; (2) mapping of sand and gravel lenses in till; (3) detection of salt or brackish water interfaces in freshwater aquifers; and (4) determination of hydrostratigraphy. These groundwater problems require determination of the depth to bedrock; location of resistive, high-porosity zones associated with fresh water; determination of formation resistivity to assess water quality; and …

Surface Sediment Composition And Distribution In Hillsborough Bay, Florida 1986, City Of Tampa Department Of Sanitary Sewers Bay Study Group

Reports

Surface sediments were mapped to determine the approximate boundaries and percent areal coverage of "mud" in Hillsborough Bay. Depth recorder soundings along 29 transects were used in conjunction with sediment grain size analyses form 19 stations to produce a sediment map.

Geophysical And Hydrogeological Effects Of Astorm-Water Retention Pond On The Floridan Aquifer, Hillsborough County, Florida, Abdullah M. Alamri

USF Tampa Graduate Theses and Dissertations

An integrated geologic, hydrologic, and geophysical investigation was conducted to determine the effect of a storm-water retention pond on the Floridan aquifer. Surface DC resistivity surveys were used to delineate the hydrostratigraphy. There are four distinct geoelectric layers: (1) Layer 1, high resistivity, 3 meters thick, fine to very fine unsaturated sand; (2) Layer 2, moderate resistivity, 1 to 2.5 meters thick, saturated sands and silts; (3) Layer 3, lower resistivity, 4 to 10 meters thick, silt and clay; (4) Layer 4, moderate resistivity, argillaceous limestone. Two fracture zones are defined by resistivity lows and marked by deep, V-shaped depressions …