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Third Grade Study Guide
Forces that Shape the Land Exam
Test Date: November 29th, 2007
Study this information for our Forces that Shape the Land test. Study everything because a variety of
questions will be on your test. You will have multiple choice, matching, and write in questions.
Earth Layers
The core is at the center of the Earth. It is made of very hot iron and nickel.
The inner core is hotter than the mantle. Scientists think it stays solid because the weight of the whole
planet presses on the inner core.
The outer core is made up of liquid rock called magma.
The mantle is the middle layer of the Earth. The rocks in the mantle are soft like taffy.
The crust is the solid outside layer of the Earth. The crust contains the rock of the ocean floor and large
areas of land called continents. The crust also contains landforms, which are natural shapes or features
of Earth’s surface.
Landforms
Mountain-place on Earth’s surface that is much higher than the land around it. It must be at least 600
meters higher than the surrounding land. Lower, similar, landforms would be called hills.
Valley-a lowland area between higher lands such as mountains.
Canyon-a deep valley with very steep sides.
Plain-a flat area on Earth’s surface. The middle of the United States is a large plain. Corpus Christi is on
a coastal plain.
Plateau-a flat area higher than the land around it. In some places plateaus have steep sides. They look
like tables made out of rock.
Barrier Island-a thin island near a coast, with wide, sandy beaches. Our school is on a barrier island!
Landform Changes
Slow changes:
Rapid changes:
Weathering-wind, flowing water, freezing water,
Earthquake-the shaking of Earth’s surface caused by
and plant roots break rocks down into smaller
movement of the crust and mantle.
pieces.
Volcano-an opening in Earth’s surface from which lava flows.
Erosion-the movement of weathered rock and soil.
Flood-a large amount of water that covers normally dry land.
Glaciers are huge sheets of ice that cause erosion
Rocks Minerals and Fossils
Mineral-a solid object formed in nature, and has never been alive. 3 properties of minerals: hardness,
shape, and color
Rock-an object made up of one or more minerals. We studied 3 types of rocks:
1. Igneous- a rock that was once melted but has cooled and hardened.
2. Sedimentary-rocks that form from material that has settled into layers. The layers are squeezed
until they harden into rock.
3. Metamorphic-rocks that are igneous or sedimentary that has been changed by heat or pressure.
The Rock Cycle is a series of processes in which one type of rock changes into another.
Fossil-something that has lasted from a living thing that died a long time ago. We studied 5 types of
fossils:
1. Petrified fossils form when minerals slowly take the place of original, once-living material.
2. Carbon fossils form when heat and pressure force out most of the materials of the once-living
thing. Only a thin film, or sheet, of black carbon is left.
3. Mold-a mold is an imprint made by the outside of a dead plant or animal
4. Cast when sediments or minerals fill a mold it forms a cast.
5. Trace fossils show changes long-dead animals made in their surroundings. Tracks, burrows,
droppings, and wormholes, are examples of trace fossils.
Soils
Soil is the loose material in which plants can grow in the upper layer of Earth. Four things make up soil:
weathered rock (minerals), air, water and humus.
Humus is the part of soil made up of decayed parts of once-living things.
Soil forms in layers:
Topsoil is the top layer of soil and it is made up of the smallest grains and contains the most humus.
Subsoil the layer under the topsoil.
Bedrock is the solid rock under soil.
Soil types:
Clay-soil made up of very small grains.
Sand-soil with large grains, less humus, and large spaces between grains.
Loam-a topsoil rich with humus, water and air.
Soil is an important resource. A resource is a material found in nature that living things use, such as
water, trees, air and minerals. It is important to conserve, or use resources carefully. One way to save and
conserve soil is through strip cropping, which is planting strips of thick grass or clover between strips of
crops. Another way to save and conserve soil is through contour plowing, which is planting rows of
crops around the side of hills instead of up and down. Plants play a huge role, anchoring our soil, and
minimizing our loss of a valuable resource, soil.
SAMPLE QUESTIONS
1. We made imprints of objects in clay to learn more about
a. weathering
b. fossils
c. renewable resources
2. In which of these ways do volcanoes help build up new land?
a. By adding heat to Earth’s surface
b. By adding gases to the atmosphere
c. By adding lava to Earth’s surface
Fill In The Blank.
Mountains
Minerals
Canyons
Igneous
Core
Fossils
Plateaus
Resources
Use the words in the box to fill in the answers:
4. The __________ is divided into inner and outer layers.
5. __________ were never alive.
6. We made models of landforms such as _______, _________, and ________.
7. A rock formed by cooling lava is an ___________ rock.
8. It is very important that we conserve our __________________.
9. Which one of these is NOT one of the four things that make up soil?
a. air
b. water
c. rubber
d. minerals