Mrs. McCarthy’s MCAS Review

Earth Science

7th Grade Curriculum–Mapping the Earth–Earth’s Structure

–Heat Transfer–Earth’s History

–The Earth in the Solar System

Mapping the Earth

• Recognize, Interpret, & Create models of Earth’s Features with Mapping.

Topographic Maps show the elevation of an area of land using contour lines.

Earth’s StructureThe Layers of the Earth

Crust- Solid, Oceanic & Continental

Mantle- Largest Layer with lithosphere & asthenosphere; convection currents

Outer Core- Liquid Molten Metal

Inner Core- Dense; Solid; Iron

Heat Transfer• Heat moves in predictable ways

from warm objects to cooler objects

• Heat Energy Moves in 3 ways:• Conduction• Convection• Radiation

Conduction :occurs Conduction :occurs when energy is when energy is passed directly from passed directly from one item to anotherone item to another

ConvectionConvection : movement of

gases or liquids from a cooler spot to a warmer spot.

Examples- Air Masses, Earth’s Mantle; Ocean

ConvectionConvection : movement of FLUIDS (GAS OR LIQUID)

from a coolercooler spot to a warmerwarmer spot.

BOILINGBOILING

WINDWIND

EARTH

Radiation :The sun's rays travel in straight lines called heat rays. When sunlight hits the earth, its radiation is absorbed or reflected.

Darker surfaces absorb more of the radiation and lighter surfaces reflect the

radiation.

What are the 3 major factors that effect a region’s climate?

1. Latitude

• Locations closer to Earth’s equator will be warmer

• Locations closer to Earth’s poles will be cooler

2. Elevation

• Higher elevations such as mountain peaks will be cooler than low elevations such as valleys

3. Distance to Coast• Coastal regions near Earth’s oceans will

be effected by water temperature and ocean breezes

• Why?: Because water holds its temperature longer than air and land

Example: Cape Cod is usually warmer than the rest of Massachusetts in the winter and cooler in the summer because it is surrounded by ocean water.

Earth’s History

Millions of years ago all of Earth’s land masses were together in one large super continent called Pangaea.

Over time Pangaea spread apart due to continental drift and sea-floor spreading.

Today, we have 7 continents on Earth.

EvidenceEvidence of the Continental Drift Theory

include:• Physical Evidence (Puzzle-like Continents)

• Fossil Evidence

• Glacial Evidence

• Climate Evidence

• Plant Evidence

Africa

South

America

The Changing Surface• In addition to plate tectonics, Earth’s

surface is ever changing due to:

–Earthquakes

–Volcanoes–Weathering, Erosion & Deposition

• Earthquakes occur when Earth’s plates shift and cause shaking on the surface

• Most Earthquakes occur at Plate Boundaries

• A Tsunami is a tidal wave in the ocean caused by tectonic (Earthquake) movement of Earth’s plates.

Most volcanoes form at plate boundaries

• Diverging- mid ocean ridge, rift valley

• Converging- island arcs/ Mt. St. Helens

• Hot spots- not on a boundary- Hawaii

Rock is broken into smaller pieces by:

• Freezing & Thawing• Release of Pressure• Growth of Plants• Action of Animals• Water• Abrasion

Earth in the Solar SystemAll objects are affected by GRAVITY. Gravity’s force is stronger on larger objects. Our solar system is held together by the Sun’s gravity. The Sun’s gravity keeps the planets orbiting around it.

Just as the planets orbit around the sun due to the Sun’s strong gravity, the moon orbit’s Earth due to Earth’s Gravity.

The moon rotates on its axis and revolves around Earth at the same rate, that’s why only one side of the moon is visible from Earth.

                                                               

Phases of the Moon

Lunar PhasesThe Moon appears to go through a complete set of phases as viewed from the Earth because of its motion around the Earth, as illustrated in the following figure.

Lunar Eclipses

During a Lunar Eclipse, the Sun, Earth, & Moon align so that the moon is not reflecting any of the Sun’s light. The moon is not visible from Earth at this time.

Solar Eclipses

During a Solar Eclipse, the Sun, Moon, & Earth align so that the Sun’s light is not reflecting on Earth. The Sun is not visible from Earth at this time.

Day & Night• Earth rotates on its axis once every 24

hours (1 day).

• When Earth is turned toward the Sun, it is daytime.

• When Earth is turned away from the sun, it is nighttime.

Earth revolves around the sun once every 365 ¼ days (1 year).

When the Northern Hemisphere is angled toward the Sun (direct rays), it is summer.When Northern Hemisphere is angled away from the sun (indirect rays), it is winter.

Summer in N.H.

Winter in S.H.

Winter in N.H.

Summer in S.H.

UNIVERSE

GALAXIES

SOLAR SYSTEMS

PLANET

• The Universe is made of billions of Galaxies

• Galaxies are made of billions of Stars• We live in the Milky Way Galaxy• The Sun is the only Star in Our Solar

System • We live on Planet Earth

UNIVERSE

GALAXIESSOLAR SYSTEM

PLANET