How Does Earth S Surface Change Over Time?
Name: ______Date: ______Per: ______
How does Earth’s surface change over time?
Model A:All changes on Earth’s surface take place slowly over time / Model B:
All changes on Earth’s surface are caused by sudden events
Directions:
1. Before continuing, circle the model above that you think is correct. DO NOT go back and change your answer even after reading the evidence.
2. Read all of the evidence below. After each piece of evidence, discuss evidence quality. Rate each piece of evidence from a 0 to 3, where 0 is the worst and 3 is the best. Then write key points from the evidence that proves it supports one of the models.
Evidence #1 Grand Canyon
Over geologic time, thousands of feet of limestone, shale, and sandstone layers are deposited. The formation of the Grand Canyon was accomplished by the constant weathering and erosion of those rocks by the Colorado River over the course of 17 million years. Over time the river was able to carve a very deep channel into the Colorado Plateau. Geologist John Wesley Powell estimated that the Grand Canyon is being eroded at a rate of 0.3 meters (1 foot) every 200 years. The Colorado Plateau, the geologic area where the Grand Canyon is located, is a very stable area. Geologists expect the Grand Canyon to continue to deepen as long as the Colorado River flows.
Evidence #2 Landslide
Landslides take place when dirt, pebbles, rocks and boulders slide down a slope together. Sometimes these landslides are small, and hardly noticeable. Other times however, they can be substantial, involving the entire side of a mountain.
In January 1997, several large landslides closed Highway 50 between Placerville and South Lake Tahoe, California. As the slide progressed down, it can pick up tremendous speed, and energy. Landslides have been “caught on tape” going at speeds approaching 200 miles per hour!
The U.S. Geological Survey, in cooperation with the Eldorado National Forest, has installed monitoring instruments on the Cleveland Corral landslide that has the potential to affect Highway 50 in the future. Data from these instruments are used to detect changes in local conditions including:
•Movement data from displacement sensors
•Ground vibration from geophones.
Large changes in these conditions, indicates a landslide may be occurring soon. By using this data, scientists can close highway 50 for the safety of the drivers.
Evidence #3 FMS Principal
Dr. Davenport at FMS is always so busy and rushing around the school that he says “Changes happen fast at FMS so they must happen fast on land.”
Evidence #4 Niagara Falls
The formation of the falls began at the end of the Ice Age. Large torrents of water were released from the melting ice, draining into what is now the Niagara River. Some 12,000 years ago, the water plunged over the edge of the Niagara Escarpment, a cliff at what is now Lewiston, New York. The force of the water wore away the rock layers and Niagara Falls moved upstream, eventually reaching its present location.
The Niagara Falls formation is a slow process that continues today. Geologists surveying the falls, have estimated that due to the rate of weathering, Niagara Falls has moved backs 7 miles in 12,500 years The annual freezing and thawing of the Niagara River still wears away at the rocks under the surface. Gradual erosion and periodic rock falls steadily move Niagara Falls farther upstream.
Evidence #5 Earthquakes and Tsunamis
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Tsunamis are generated from underwater earthquakes of a 6.2 magnitude or greater. Seismologists from the USGS looked at several pieces of data and determined the earthquake in Japan was a magnitude of 9.0 and was able to trace the epicenter of the earthquake to the Sea of Japan. Below are satellite images taken by NASA of an area just north of Sendai, Japan. The images on the left were taken on June 25, 2010 before the earthquake and tsunami and the images on the right were taken on March 12, 2011 after the earthquake and tsunami.
#1. Grand Canyon. Colorado River shaped rock into the present-day Grand Canyon.
#2. Landslides. The landslide in Lake Tahoe, CA changed the landscape along highway 50.
#3. Dr. Davenport. Dr. Davenport says, “Change happens fast at FMS.”
#4. Niagara Falls. The force of the water wears away the rock layers of the falls to change its shape.
#5. Earthquakes. The earthquake in Japan caused a tsunami that changed the coastline of Japan.
Directions Continued…
3. After reading each piece of evidence and filling in the chart, discuss which model is correct. If you feel that both are incorrect, use the space below to create a new model or revise one of the given models to make it accurate. Work in pairs or individually.
How the Earth’s Surface Changes Model
Name: ______
Date: ______
How does Earth’s surface change over time?