Topography The description and mapping of the physical features of the Earth’s surface

Topographic Maps A map of Earth’s surface showing elevation

Contour Lines Lines drawn on a map connecting points of equal elevation – The closer the contour lines, the steeper the elevation.

Contour Interval Contour Interval: – The increase in elevation between contour lines.

Index Contour Interval Bolded Contour lines with a marked elevation

Benchmark Point where exact elevation is known and in marked with a brass plate BM will mark the benchmark on a map

Geologic Processes That Cause Change Weathering – Break down of rock into smaller pieces. Erosion – movement of sand, soil and rock Deposition – settling and layering of sand, soil and rock.

Causes of weathering, erosion and deposition of Earth Wind Water – rivers, waterfalls, streams, oceans, rain, ice Plate tectonics – Mountains, trenches, ridges, rift valleys, fault lines Earthquakes Volcanoes Plants and animals including humans

Change in topography of Mount St. Helens after it erupted in 1980

What can you predict from a topographic map? -Look at the topographic map 1. -Now look at the topographic map 2 -Decide which image matches map 1, and which image matches side map 2.

1 2

Mt. St. Helens before the eruption in 1980

Mt. St. Helens after the eruption in Debris from the side of the was Mountain as well as ash was launched into the air and settled as much as 230 miles away. What type of geologic process is this?

Using topographic maps can help you predict the outcome of catastrophic events, and it can also help you to determine a type of landform.

What land form is shown above?

What is the landform shown here? What is the greatest elevation this landform could have? What is the biggest danger for this landform in terms of geologic processes?

This area of New Jersey was hit hard by Hurricane Sandy. If a new topographic map was made of this area after the storm surge (higher than normal tide) was gone, what is one thing you think would look different. Remember, topographic maps only show land features and elevations, not houses. The hurricane moved across this area from the front( beach area) to the back (where the green island is)

A new topographic map would show less land because both the front and side beaches are gone due to erosion. There are many channels in the front side of the island now that would be shown on a new topographic map. The area where the front of the island was likely deposited is not above sea level, so it would not be shown, however, it is likely that the back of the island could have a higher elevation now if some of the sand was deposited there. may now have a higher elevation Not above sea level

Using satellite images can also help predict consequences of catastrophic events. In 2011, the Mississippi River was carrying more water than normal due to heavy rains and snow melting. When this water arrived in New Orleans it would have caused extensive flooding. A spillway was opened to provide an extra way for the water to get to the Gulf, but for some unknown reason, almost all of the sediment carried by the river went out the new spillway. What formed because of this in the area where the spillway met the Gulf?

A new delta formed due to what geologic process?