If you fly over Nevada, look out the window at the landscape below. Nevada is a series of valleys and ridges that make up a large region called the Basin and Range. The alternating lowlands and highlands are there because Nevada is being stretched from below in part of a tectonic process that will probably open up the state to ocean water encroaching from the south. Yes, dry Nevada will partially become a sea (Not this week, if you’re planning a trip to Las Vegas or Reno).
Nevada isn’t without water, however. Snows and rains do fall, and they form streams that wear away the highlands. Erosion leads to deposition. The rocks of the highlands become the sediments that cover their lower flanks in coalescing fan-shaped aprons. With repeated deposits of debris washed from the higher elevations, the fans of sediment spread out, overlap, and eventually make a sloping embankment called a bajada. Bajadas are piles of rock debris (from boulders to cobbles to pebbles to sands) clearly visible from a high-flying jet.
Highlands throughout the world undergo constant attack by erosional forces. Landslides and rock falls make dramatic and quick changes. Ice and water usually act a little more slowly, but they effect most of the change. And at times big downpours in desert storms can wash large volumes of material downslope.
That the erosion of a highland leads to the development of a bajada is like much of what happens when humans, like Nevada’s ranges, are elevated. Erosion of every highland is inevitable, and in the case of human interactions, the agents of erosion are legion. Seems that some of those in the valleys can only scale the highlands on slopes of debris, material sometimes deposited in catastrophic collapses and at other times deposited by an infrequent, but inevitable rainfall.
Some of those who live on the slopes of highlands seem happy with the debris. They attempt to level the landscape not by elevating themselves, but by wearing down the highlands. Today, from the altitude of an airplane, the differences in the landscape are both noticeable and remarkable. From the perspective of distant time, only those highlands that escape complete erosion will stand above an encroaching sea.
Nevada isn’t without water, however. Snows and rains do fall, and they form streams that wear away the highlands. Erosion leads to deposition. The rocks of the highlands become the sediments that cover their lower flanks in coalescing fan-shaped aprons. With repeated deposits of debris washed from the higher elevations, the fans of sediment spread out, overlap, and eventually make a sloping embankment called a bajada. Bajadas are piles of rock debris (from boulders to cobbles to pebbles to sands) clearly visible from a high-flying jet.
Highlands throughout the world undergo constant attack by erosional forces. Landslides and rock falls make dramatic and quick changes. Ice and water usually act a little more slowly, but they effect most of the change. And at times big downpours in desert storms can wash large volumes of material downslope.
That the erosion of a highland leads to the development of a bajada is like much of what happens when humans, like Nevada’s ranges, are elevated. Erosion of every highland is inevitable, and in the case of human interactions, the agents of erosion are legion. Seems that some of those in the valleys can only scale the highlands on slopes of debris, material sometimes deposited in catastrophic collapses and at other times deposited by an infrequent, but inevitable rainfall.
Some of those who live on the slopes of highlands seem happy with the debris. They attempt to level the landscape not by elevating themselves, but by wearing down the highlands. Today, from the altitude of an airplane, the differences in the landscape are both noticeable and remarkable. From the perspective of distant time, only those highlands that escape complete erosion will stand above an encroaching sea.
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