Digital Data from the Great Sand Dunes and Poncha Springs Aeromagnetic Surveys, South-Central Colorado

2009 ◽  
Author(s):  
B.J. Drenth ◽  
V.J.S. Grauch ◽  
Viki Bankey ◽  
Ltd. New Sense Geophysics
Keyword(s):  
Sand Dunes ◽  
Digital Data ◽  
South Central

scholarly journals Digital data from the Great Sand Dunes airborne gravity gradient survey, south-central Colorado

2013 ◽  
Author(s):  
B.J. Drenth ◽  
J.D. Abraham ◽  
V.J.S. Grauch ◽  
V.F. Labson ◽  
G. Hodges
Keyword(s):  
Sand Dunes ◽  
Digital Data ◽  
Airborne Gravity ◽  
Gravity Gradient ◽  
South Central

Seed bank dynamics of blowout penstemon in relation to local patterns of sand movement on the Ferris Dunes, south-central Wyoming

Botany ◽  
2017 ◽  
Vol 95 (8) ◽  
pp. 819-828 ◽  
Author(s):  
Kassie L. Tilini ◽  
Susan E. Meyer ◽  
Phil S. Allen
Keyword(s):  
Seed Bank ◽  
Plant Density ◽  
Sand Dunes ◽  
Near Surface ◽  
South Central ◽  
Secondary Dormancy ◽  
Seed Bank Dynamics ◽  
Buried Seeds ◽  
Sand Movement ◽  
Persistent Seed Bank

Plants restricted to active sand dunes possess traits that enable both survival in a harsh environment and local migration in response to a shifting habitat mosaic. We examined seed bank dynamics of Penstemon haydenii S. Watson (blowout penstemon) in relation to local sand movement. We measured within-year sand movement along a 400 m transect and examined plant density, seed production, and seed density in relation to this movement. Plant densities were highest in areas of moderate sand movement. Annual seed rain averaged 13 seeds·m−2, whereas persistent seed bank density (0–10 cm depth) averaged only 0.1 seeds·m−2. A laboratory burial experiment with nondormant (chilled) seeds showed that most deeply buried seeds (>6 cm) were held in enforced dormancy under spring conditions, while seeds at intermediate depths (4–6 cm) were induced into secondary dormancy that was broken by subsequent drying and re-chilling, thus promoting seed carryover until the following spring. Most near-surface seeds produced seedlings. Enforced and secondary dormancy provide mechanisms for maintaining a persistent seed bank of more deeply buried seeds that could become part of the active seed bank as sand movement re-exposes them near the surface. This could facilitate both population persistence and migration as previously occupied habitat becomes unsuitable.

scholarly journals Holocene Eolian Activity in South-central Saskatchewan and the Southern Canadian Prairies*

2004 ◽  
Vol 56 (2-3) ◽  
pp. 215-227 ◽  
Author(s):  
Stephen A. Wolfe ◽  
Jeff Ollerhead ◽  
Olav B. Lian**
Keyword(s):  
Boreal Forest ◽  
Late Holocene ◽  
Sand Dunes ◽  
Canadian Prairies ◽  
South Central ◽  
South Saskatchewan River ◽  
Dune Stability ◽  
Eolian Deposits ◽  
Forest Boundary ◽  
Dune Activity

Abstract The chronology and stratigraphy of eolian deposits at two sites in south-central Saskatchewan were studied in order to extend the spatial and temporal record of dune activity on the Canadian prairies. Optical ages document the timing of valley-infilling by sand dunes in the Qu’Appelle River area, and of cliff-top eolian deposition along the South Saskatchewan River. These ages, along with published radiocarbon and optical ages, are used to develop a chronology of eolian activity for south-central Saskatchewan. Optical ages of eolian sands ranging from 5.7 to 0.14 ka (before AD 2000), with intervening paleosols, indicate alternating periods of eolian activity and dune stability during the late Holocene, supported by published radiocarbon ages. Other published radiocarbon ages ranging from 11.3 to 8.4 cal ka BP indicate early Holocene eolian activity. Mid-Holocene ages are predominantly absent from the chronology and this is interpreted as being due to extensive eolian reworking during at least the latter part of the mid-Holocene. The chronology in south-central Saskatchewan is similar to other parts of the southern Canadian prairies. It is likely that preserved mid-Holocene eolian deposits occur within depositional basins in the southern Canadian prairies, and at sites near the southern boreal forest boundary with the prairie ecozone.

Automated Least-Cost Pipeline Route Development in Niger Using Remotely-Sensed Imagery and GIS

2010 ◽  
Author(s):  
David L. Slayter ◽  
Christopher S. Hitchcock ◽  
Mike Oehlers ◽  
Richard Chiles
Keyword(s):  
Sand Dunes ◽  
Remotely Sensed ◽  
Oil Field ◽  
Geologic Mapping ◽  
Remotely Sensed Imagery ◽  
South Central ◽  
Geologic Hazards ◽  
Anthropogenic Development ◽  
Transmission Pipeline ◽  
Pipeline Route

An important part of successful pipeline route selection includes the identification of geologic hazards and man-made (anthropogenic) features along any proposed route. Fugro William Lettis & Associates, Inc. (Fugro WLA) was contracted to provide a preferred crude oil transmission pipeline route between the Agadem oil field and the Zinder refinery in south-central Niger. The development of the 460-km long, 500-meter wide corridor involved the use of new geologic mapping and a digital elevation model (DEM) derived from Satellite Pour l’Observation de la Terre (SPOT) remotely-sensed imagery and SPOT High Resolution Stereo (HRS), respectively. The base geologic, anthropogenic and DEM data were provided by Fugro NPA Ltd. (Fugro NPA) and augmented with additional mapping by Fugro WLA. The area of the proposed pipeline route covers varying geologic conditions such as active and relict sand dunes, bedrock outcrops and escarpments, wadis and areas of recent erosion. Anthropogenic features included reservoirs, roads, towns and settlements, agricultural areas and oases. Our study found significant height differences between the dunes and evidence for varying dune activity. Selection of the optimal pipeline route required minimization of total elevation change and exposure to geologic hazards and existing anthropogenic development while obtaining the safest, most direct and economic route between the oil field and refinery. Using a geographic information system (GIS) the digitally-mapped geologic and anthropogenic features and elevation-derived parameters were assigned a relative risk ranking surface. Next, a cumulative cost distance surface and a cost path surface were created between the oil field and the refinery. Lastly, using GIS we developed a least-cost pipeline route option from the cost path surface.

Practical applications of scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 18-19
Author(s):  
D. R. Denley
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Quantitative Information ◽  
Digital Data ◽  
Scanning Tunneling ◽  
Ambient Atmosphere ◽  
Tunneling Microscopy ◽  
Clear Trend ◽  
Practical Applications ◽  
Promising Tool

Scanning tunneling microscopy (STM) has recently been introduced as a promising tool for analyzing surface atomic structure. We have used STM for its extremely high resolution (especially the direction normal to surfaces) and its ability for imaging in ambient atmosphere. We have examined surfaces of metals, semiconductors, and molecules deposited on these materials to achieve atomic resolution in favorable cases.When the high resolution capability is coupled with digital data acquisition, it is simple to get quantitative information on surface texture. This is illustrated for the measurement of surface roughness of evaporated gold films as a function of deposition temperature and annealing time in Figure 1. These results show a clear trend for which the roughness, as well as the experimental deviance of the roughness is found to be minimal for evaporation at 300°C. It is also possible to contrast different measures of roughness.

Convergent-beam thickness determination: The advantages of digital imaging

1994 ◽  
Vol 52 ◽  
pp. 420-421
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Intensity Variation ◽  
Convergent Beam Electron Diffraction ◽  
Digital Data ◽  
Thickness Determination ◽  
Frequent Use ◽  
Automated Processing ◽  
Beam Thickness ◽  
Convergent Beam ◽  
Remarkable Agreement

Convergent-beam electron diffraction (CBED) patterns contain an immense amount of information relating to the structure of the material from which they are obtained. The analysis of these patterns has progressed to the point that under appropriate, well specified conditions, the intensity variation within the CBED discs may be understood in a quantitative sense. Rossouw et al for example, have produced numerical simulations of zone-axis CBED patterns which show remarkable agreement with experimental patterns. Spence and co-workers have obtained the structure factor parameters for lowindex reflections using the intensity variation in 2-beam CBED patterns. Both of these examples involve the use of digital data. Perhaps the most frequent use for quantitative CBED analysis is the thickness determination described by Kelly et al. This analysis has been implemented in a variety of different ways; from real-time, in-situ analysis using the microscope controls, to measurements of photographic prints with a ruler, to automated processing of digitally acquired images. The potential advantages of this latter process will be presented.

Sign in / Sign up

Export Citation Format

Share Document