The 3-D visualization and cross sections help in the understanding of the geometrical relationship between the different geologic features, allowing a reexamination of the tectonic history of the area during the late Mesozoic. The case study chosen to illustrate the method is the Beirut watershed (Lebanon), an area with relatively simple geology. To illustrate how a 3-D geologic map can be computed, we explain the steps taken to build a dummy model with simple faulting and depositional sequencing. The major advantage of using such technology is that it provides the user with a way to quantify geology.
Earthview withgoogle mauritania nouakchott series#
It is based on a modeling algorithm that only, uses surfaces calculated from scattered data points and that intersects them following a series of geologically sound rules. The method is innovative in that it only uses surface information based on the combination of a standard geologic map, a satellite image, and a digital elevation model. We present a way to produce mathematically and geometrically correct three-dimensional (3-D) geologic maps consisting of the volume and shape of all geologic features of a given area. City-Swallowing Sand Dunes from NASA Exploration Systems.Recent discoveries in earth sciences are mostly related to technologies allowing graphical representations of volumes.Forecasting Dust Storms from the University Corporation for Atmospheric Research.Preventing sand dunes from overwhelming cities and agricultural areas has become a priority for the United Nations Environment Programme. Sand fences might also work, but researchers are still trying to figure out the best possible fence design. Drenching sand dunes with oil stops their migration, but this approach hurts the environment and uses a finite resource. Sand threatens buildings and crops not only in Africa, but also the Middle East and China. And like snow, sand avalanches, falling down the steep slopes of the dunes that face away from the winds, also moving the dunes forward. In a major dust storm, dunes may move tens of meters through such sheet flows. With slightly stronger winds, particles collide in mid-air, causing sheet flows.
When these skipping particles land, they may knock into other particles and cause them to skip as well. One way that dunes can move is through saltation, where sand particles skip along the ground like a rock thrown across a pond might skip across the water’s surface. Sand dunes move through a few different means, all of them helped along by wind. Although they look appealing in a satellite image, these dunes threaten to overtake the city. Hot on the city’s heels are sand dunes, appearing as salmon-tinged beige ripples. In this image, the city of Nouakchott appears in charcoal gray, and its features cover the landscape in a typical grid-like urban pattern.
Earthview withgoogle mauritania nouakchott plus#
The Enhanced Thematic Mapper Plus (ETM+) instrument on NASA’s Landsat satellite captured this photo-like image of Nouakchott on January 9, 2001. Even for the coastal capital, Nouakchott, Saharan sands pose daily challenges for the city’s inhabitants. Mauritania lies along the west coast of northern Africa, and holds part of the Sahara Desert. This city may be slowly obliterated by nature-not by creeping green vines run amok, but by creeping dunes of sand. Such is the case in Nouakchott, the capital of Mauritania.
While many worry about urban areas slowly engulfing nearby nature, once in a while the tables are turned.
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