نتایج جستجو برای: bedrock

تعداد نتایج: 3327  

2005
Rick Olson Caroline Noble

Karst landscape overview THE 52,830 ACRES OF MAMMOTH CAVE NATIONAL PARK are part of the South-Central Kentucky Karst, which is characterized by subterranean drainage to springs on major rivers. From the southeast to the northwest portion of the landscape (Figure 1), there is a gradient of decreasing maturity in karst development, which corresponds to the regional dip of the bedrock. The major c...

2015
Bethany L. Ehlmann Jennifer Buz

A 500 km long network of valleys extends from Herschel crater to Gale, Knobel, and Sharp craters. The mineralogy and timing of fluvial activity in these watersheds provide a regional framework for deciphering the origin of sediments of Gale crater’s Mount Sharp, an exploration target for the Curiosity rover. Olivine-bearing bedrock is exposed throughout the region, and its erosion contributed t...

2014
Christian Hirt

Accurate knowledge of Antarctica’s topography, bedrock, and ice sheet thickness is pivotal for climate change and geoscience research. Building on recent significant progress made in satellite gravity mapping with European Space Agency’s Gravity field and Ocean Circulation Explorer (GOCE) mission, we here reverse the widely used approach of validating satellite gravity with topography and inste...

2004
Jon D. Pelletier

[1] Numerical landscape evolution models driven by uniform vertical uplift often develop a static drainage network and a precise balance between uplift and erosion. Small-scale physical models of uplifting drainage basins, however, continually reorganize by ridge migration and do not reach an ideal steady state. Here I show that the presence or absence of persistent drainage migration in a bedr...

Journal: :Journal of water and health 2008
Sylvi Gaut Lucy Robertson Bjørn Gjerde Atle Dagestad Bjørge Brattli

The occurrence of Cryptosporidium oocysts and Giardia cysts in Norwegian groundwater wells in bedrock has been investigated for the first time. Wells close to risk areas such as farming and septic tanks were chosen. In all, 20 water samples from 20 different waterworks were collected. The samples were analysed for Cryptosporidium and Giardia, using US EPA Method 1623. Turbidity was also measure...

2000
J. B. Harris

Shallow shear wave reflection surveys using high frequency vibroseis techniques provides information about the Tertiary bedrock surface and Pleistocene sediments on the Fraser River delta, in B.C., Canada. Besides the clear advantage of shear wave profiling in this shallow gas environment, the added resolution potential and ability to measure the shear wave velocity field enhances the fusion of...

2005
I. Baron G. B. Crosta

Deep-seated slope failures are common features in the mountains of the Raca Unit, Magura Nappe of the Flysch Belt of Western Carpathians. Since they represent very complicated system, understanding of their evolution and triggers still remains unclear. We tried to provide a back-analysis of their development by using a finite difference code (FDM) of continua (Flac 4.0). We confirmed that such ...

2004
Kelin X. Whipple

■ Abstract Bedrock rivers set much of the relief structure of active orogens and dictate rates and patterns of denudation. Quantitative understanding of the role of climate-driven denudation in the evolution of unglaciated orogens depends first and foremost on knowledge of fluvial erosion processes and the factors that control incision rate. The results of intense research in the past decade ar...

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