Nature’s Architecture: Landforms Created by Erosion Quiz

If a river flows over a high plateau and has high velocity, then it will exert downward force on the bedrock; if this downward erosion continues for millions of years, then a deep, steep-walled valley known as a canyon is formed.

If a glacier moves through a pre-existing valley, and if the ice is heavy enough to pluck and abrade both the bottom and the sides simultaneously, then the valley will widen and flatten; this results in a "U" shape known as a glacial trough.

If waves strike a rocky headland, then they focus energy on weak points to form sea caves; if the erosion continues from both sides or pierces through the back of the cave, then a hollow arch remains above the water.

If a sea arch is continuously weathered and eroded by waves, then the roof of the arch becomes too weak to support its own weight; if the roof collapses, then an isolated pillar of rock called a sea stack is left standing in the ocean.

If a glacier begins to form in a mountain hollow, and if the freeze-thaw cycle and plucking pull rock away from the mountain wall, then a deep, amphitheater-like basin called a cirque is created.

If two glaciers erode parallel U-shaped valleys, then the rock wall separating them becomes increasingly thin; if the erosion continues until only a narrow, knife-like ridge remains, then that landform is called an arete.

If wind carries sand particles close to the ground, then the lower part of a rock outcrop is hit by more abrasive "sandblasting" than the top; if the base erodes faster than the top, then a mushroom-like shape is produced.

If a landform is shaped by the mechanical or chemical force of flowing liquid water, then it is a water-erosion feature; V-shaped valleys, waterfalls, and meanders are fluvial (river) features, and sea caves are coastal water features.

If a plateau is a large, flat area of land elevated high above sea level, and if it is formed by tectonic uplift or lava flows rather than wind-blown dust (loess), then the statement that it is created by wind deposition is false.

If a small tributary glacier joins a much larger, deeper main glacier, and if the main glacier carves a much deeper trough, then when the ice melts, the floor of the tributary valley will be high above the main valley floor; this creates a "hanging" appearance.

If wind blows across a desert floor, and if it is strong enough to lift small silt and sand but not heavy pebbles, then only the larger rocks remain; this process of "blowing away" the fine material is known as deflation.

If multiple cirque glaciers erode the sides of a single mountain peak from different directions, and if they meet at a central point, then the peak is sharpened into a steep, multi-sided pyramid known as a horn.

If water moves faster on the outside of a curve, then it will erode the bank (cut bank); if water moves slower on the inside, it drops sediment (point bar); if this dual process continues, the river develops a snake-like "meander."

If a patch of protective vegetation is removed in a dry area, and if the wind begins to lift and remove the exposed loose soil and sand, then a bowl-shaped hole called a blowout is formed in the landscape.

If waves constantly crash against the base of a rocky shore, then they undercut the rock; if the upper part of the rock loses its support and collapses into the sea, then a vertical or near-vertical sea cliff is formed.

If a glacier carves a deep U-shaped valley all the way to the coast, and if the glacier melts and the sea level rises to fill that valley, then a deep, narrow coastal inlet called a fjord is created.

If a river flows over rocks of different hardness, and if the softer rock underneath erodes faster than the hard top layer, then an overhang is created; if the overhang eventually collapses, then a vertical drop or waterfall is formed.

If a landform is carved out by the removal of material by wind or the impact of wind-blown particles, then it is an erosional wind feature; Yardangs, mushroom rocks, and deflation hollows fit this, while sand dunes are depositional and striations are glacial.

If a river meander becomes very loopy, and if erosion breaks through the narrow neck of land between the loops, then the river takes the shorter path; if deposition seals off the old loop, then a crescent-shaped oxbow lake is left behind.

If waves erode the base of a cliff to create a notch, and if the cliff retreats inland as it collapses, then a flat or gently sloping bench of rock is left behind at the low-tide mark; this is known as a wave-cut platform.