Download Earth*s Changing Surface

Chapter 6
What is the structure of Earth?
 Crust-Earth’s outermost and thinnest layer
 Mantle-the layer that makes up most of Earth’s
material
 Core-the center of the Earth
 The outermost and thinnest layer of the Earth is called
the crust.
 There are two kinds of crust called continental crust
and oceanic crust.
 When the continental crust dips below water it forms
the continental shelf.
 The mantle is the layer that makes up most of Earth’s material.
 The top part is solid hot rock.
 The top part of the mantle and the crust above, make up the







lithosphere.
Convections currents flow slowly in the mantle.
Cooler rocks flow down and hotter rocks flow up.
The lithosphere floats on top of the convection currents.
The center of the Earth is called the core.
The inner core is solid.
The outer core is liquid.
The currents of the outer core make the Earth’s magnetic field.
 Scientists study the mantle and core by studying
mantle materials that is pushed up through the cracks
of the crust.
 Scientists study the Earth by measuring the vibrations
from Earthquakes.
 A seismograph records earthquake waves.
What causes earthquakes and volcanoes?
 Plate-a section of the lithosphere
 The lithosphere covers all of the Earth line a thin shell.
 It is broken up into several large pieces called plates.
 Earth’s plates are slowly moving.
 Small changes can cause mountains, while large
changes can cause earthquakes.
 Mountains, earthquakes and volcanoes eruptions take
place where the plates meet.
 The edges of plates are called plate boundaries.
 There are three types of boundaries.
 Converging boundaries are where two plates collide.
 Spreading boundaries form when plates move apart
from each other.
 Sliding plate boundaries is when two plates move past
each other in opposite directions.
 Destructive forces and processes wear away or tear down Earth features,







such as earthquakes.
Earthquakes most often occur on faults that are along plate boundaries.
Faults are crakes in the Earth’s crust where the surrounding rock has
moved or shifted.
Earthquakes occur when the plates get stuck as they pass each other.
The place where the plates start to slip is called a focus.
The place on Earth’s surface above the focus is called an epicenter.
Earthquakes can cause landslides, the downhill movement of large
amounts of rock and soil.
Earthquakes under the ocean can cause a tsunami, waves large enough
to destroy things when they crash into a coastline.
 Most volcanoes form near colliding plate boundaries.
 As one plate moves below another plate, rock partially
melts to make magma.
 Magma is force through to the surface through weak
spots in the crust.
 Volcanoes that come from the ocean floor form
volcanic islands when it reaches the surface of the
water.
What is weathering?
 Mechanical weathering-the breaking of rock into
smaller pieces by forces
 Chemical weathering-the changing of material in a
rock by chemical processes
 Weathering is the slow, destructive process that breaks
rock into smaller pieces called sediments.
 There are two types of weathering.
 Mechanical weathering is the breaking of rock by
forces.
 Chemical weathering is the changing of material in
rock by chemical process.
 When water freezes in the cracks of rocks, it expands
and forces rock to split apart, called ice wedging.
 Changes in pressure can cause rocks to break.
 Plant roots can grow into the cracks of rocks and break
them.
 Raindrops that absorb carbon dioxide can dissolve
parts of rocks.
 Fungi and other organism give off chemicals that
change some rocks.
 Soil is usually made up of sediments, small bits from
weathered rocks.
 Soil also contains decayed materials from organisms,
gases from air, and water.
 Soils color varies, and color depends upon what
materials are in the soil.
What is erosion?
 Erosion is the movement if materials away from place
to place.
 Gravity is the main force causing erosion, causing
landslides and river flow.
 Water causes erosion.
 When water flow slows, the ability to move sediment
lessens, and sediment is deposited, changing the shape
of where it lands.
 Constant action of waves causes erosion and
deposition on the coastline.
 Parts of the shoreline erode at different rates.
 Wind erosion is cause by wind blowing dust, soil, and
sand from one place to another.
 Sand dunes are large, loose deposits of sand.
 Wind can blow topsoil off fields, making growth
harder.
How are minerals identified?
 A mineral is a naturally occurring solid that has a
regular arrangement if particles in it.
 Minerals are found in soil and rocks.
 Properties include, smell, shape, and texture.
 To identify an unknown mineral, scientists compare
observations with observations made of known
minerals.
How are rocks classified?
 Igneous-rocks formed when melted rock cools and
hardens
 Sedimentary-rocks formed when layers of materials
and rock particles settle on top of each other and then
harden
 Metamorphic- a type of rock formed when existing
rock is heated at high pressures and temperatures.
 When melted rock cools and hardens it forms igneous
rocks.
 When layers of materials and rock particles settle on
top of each other and then harden to form
sedimentary rock.
 Plant and animal fossils are most often found in layers
of sedimentary rock.
 Rock formed when existing rock is heated at high
pressures and temperatures is called metamorphic
rock.
 Rocks can change from one kind to another in any
order, or stay the same for millions of years.
 Rock layers are put down in the order in which they are
formed.
 Younger rock is at the surface of Earth.
 Scientists who study fossils, use location within layers
of rock to determine age.