Presentation on theme: "Erosion. Rain Splash Sheet Rill Gully Heavy rains in northwest Iowa washed away soil, leaving this scarred tableau. This type of erosion, termed sheet-and-"— Presentation transcript:
Rain Splash Sheet Rill Gully Heavy rains in northwest Iowa washed away soil, leaving this scarred tableau. This type of erosion, termed sheet-and- rill erosion, occurs when there is insufficient vegetation to hold soil in place. As rain falls, it forms sheets of surface water that transport soil away. As more water accumulates, it forms runoff channels called rills, which further displace soil.
Water Runoff 40% of precipitation becomes runoff Water carries weathered rocks and sediment What factors might affect runoff? A waterfall fed by glacial runoff tumbles over sheer cliffs and into the turquoise water of Admiralty Inlet on Baffin Island, Nunavut, Canada. Such moving water is among the most powerful of nature's landscape-altering tools.
Rain – Splash Erosion Falling raindrops make small craters on ground Describe how a raindrop causes the soil to move. thering/water_erosion.html
Rain – Sheet Erosion Occurs when water can’t soak into the ground Large flow of water over land What might help prevent sheet erosion? thering/water_erosion.html
Rain – Rill Erosion Water collects into closely- spaced small channels Tend to form on steeper land What might happen to rills if they aren’t stopped? thering/water_erosion.html
Rain – Gully Erosion Steep-sided trenches Formed when rills come together Difficult to stop Why do you think it is so difficult to stop gully erosion once it has started? thering/water_erosion.html
Water – Waves Moves sand from beach to sandbars What types of events might increase erosion on beaches? The 367-mile-long Texas gulf coastline loses around 235 acres of lands to erosion each year, equivalent to more than 181 football fields of beach, according to the Texas General Land Office.
Water - Waves Not just on the beach…. Why is this type of erosion so dangerous to humans? Sandbars swirl beneath Oregon Inlet in Cape Hatteras National Seashore on North Carolina's Outer Banks. Waves driven by ocean winds can cause the sandbars here to shift and change literally by the hour.
Wind Moving air Blows loose sediment Carries abrasive particles Where do you think wind erosion might be most common? Wind erosion makes these layered sandstone hills swirl in Paria Canyon-Vermilion Cliffs Wilderness Area. The area, whose 112,500 acres straddle the Utah-Arizona border, is home to sandstone arches, huge red rock amphitheaters, and hanging gardens.
Glaciers Larges masses of moving ice & snow Push & carry rocks and sediment in front of them “Pluck” rocks & sediment from the land beneath them. Scrape rocks & sediment from valley walls. What do you think happens to the valley as a glacier moves through it? The Bernard Glacier in Alaska's Saint Elias Mountains looks like a huge alpine highway. Glaciers are slow but highly effective shapers of the land, essentially carrying away anything in their path—from soil and rocks to hills and even the sides of mountains.
Mass Wasting Process by which rock and soil move down a slope Usually as a mass Under the force of gravity What types of events would be considered mass wasting? m