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34 terms

4th grade science - Changing Earth

Harcourt 4th grade science, Unit B, Chap 1.
STUDY
PLAY
landform
a physical feature of Earth's surface
weathering
the process of breaking rock into soil, sand, or other tiny pieces
erosion
the process of moving sediment from one place to another
deposition
the process of dropping, or depositing, sediment in a new location
mass movement
the downhill movement of rock and soil because of gravity
crust
the outer layer of Earth made of solid rock
mantle
the layer of rock beneath the Earth's crust
core
Earth's hottest layer; the center layer of Earth
plate
a rigid block of crust and upper mantle
magma
hot, soft rock from Earth's lower mantle
volcano
an opening in Earth's crust through which lava flows
earthquake
a shaking of the ground caused by the sudden release of energy in Earth's crust
fault
a place where pieces of Earth's crust move
continental drift
a rigid block of crust and upper mantle
Pangea
According to theory this was a "supercontinent" that contained all of Earth's land about 225 million years ag.
fossils
the remains or traces of past life found in Earth's crust
Grand Canyon
a mile-deep slice into Earth's history - and a very popular tourist attraction
The oldest rock layer
What rock layer is found at the bottom of the Grand Canyon
How old are the oldest rocks of the Grand Canyon
250 million years old
The southern continent that existed 200 million years ago was
Gondwana
Many strong earthquakes are caused by
plates sliding past each other
How do volcanoes form where oceanic and continental plates collide?
The edge of the oceanic plate pushes under the edge of the continental plate, and then melts as it sinks into the mantle, becomes magma and forces its way up between the plates.
shield volcanoes
broad volcanoes with gentle slopes - they are mostl lava
cinder cone volcanoes
tall and narrow, with steep slopes - mostly ash
composite volcanoes
wide and have fairly steep slopes - they are lava and ash.
What parts of the Earth are solid rock
inner core, crust, upper mantle
A type of mass movement is a
glaciers
What new landforms are created by erosion and deposition
island, terminal moraines, deltas, lakes, valleys
terminal moraines
they mark the leading edge of a glacier - long ridges of soil and rock.
What are some of the forces that change landforms
water, wind, ice, mass movement
Beginning with the outermost layer, Earth's layers are the
crust, mantle, core
Wind erodes rock and deposits sediments to form
dunes
water erodes rock and dposits sediments to form
delta
Ice erodes rock and deposits sediments to form
terminal moraines