1. WEATHERING AND SOIL CH 9 8 TH GRADE

2. 9.1 ROCKS AND WEATHERING WHAT BREAKS DOWN ROCKS? IT’S A HARD ROCK LIFE EROSION PT 1 EROSION PT 2 EROSION VS WEATHERING

3. WHAT CAUSES WEATHERING? MECHANICAL: ICE & WATER, RELEASE OF PRESSURE, PLANT GROWTH, ACTIONS OF ANIMALS, & ABRASION CHEMICAL: WATER, OXYGEN, CARBON DIOXIDE, ORGANISMS, & ACID RAIN

4. HOW FAST DOES WEATHERING OCCUR? TYPE OF ROCK: DISSOLVABLE AND PERMEABLE CLIMATE: HOT AND WET, ACID RAIN RESULTS OF WEATHERING AND EROSION

5. WHAT IS SOIL? SOIL IS A MATTER OF ROCK PARTICLES, MINERALS, DECAYED ORGANIC MATERIAL, WATER, AND AIR. BEDROCK PROVIDES MATERIAL THAT IS WEATHERED INTO SMALLER PARTICLES THAT ARE THE MOST COMMON COMPONENTS OF SOIL. THE PARTICLES OF ROCK IN SOIL ARE CLASSIFIED BY SIZE AS GRAVEL (LARGEST), SAND, SILT, AND CLAY (SMALLEST). HUMUS COMES FROM DECAYING ORGANISMS AND PROVIDES SPACE FOR AIR & WATER AS WELL AS NUTRIENTS.

6. THE FERTILITY OF SOIL IS A MEASURE OF HOW WELL THE SOIL SUPPORTS PLANT GROWTH. SOIL TEXTURE DEPENDS UPON THE SIZE OF THE SOIL PARTICLES AND DETERMINES THE FERTILITY. LOAM, EQUAL PARTS CLAY, SAND, AND SILT, IS THE BEST FOR GROWING MOST PLANTS, SOIL PH SHOWS IF THE SOIL IS ACIDIC OR BASIC. SOIL WITH A PH OF 6-7.5, NEITHER ACIDIC NOR BASIC IS BEST FOR GROWING MOST PLANTS. SOIL FORMS AS ROCK IS BROKEN DOWN BY WEATHERING AND MIXES WITH OTHER MATERIALS ON THE SURFACE. SOIL FORMS AS ROCK IS BROKEN DOWN BY WEATHERING AND MIXES WITH OTHER MATERIALS ON THE SURFACE.

7. SOIL TYPES DIFFERENT TYPES OF SOIL SUPPORT THE GROWTH OF DIFFERENT TYPES OF PLANTS. MOST PLANTS GROW BEST IN FERTILE SOIL. THE THICKEST, MOST FERTILE SOIL FORMS IN CLIMATE REGIONS WITH MODERATE TEMPERATURES AND RAINFALL. IN MOUNTAINS OR POLAR REGIONS, THE SOIL IS OFTEN THIN. PLANTS ARE USUALLY SPREAD OUT BECAUSE THE SOIL ONLY HAS ENOUGH NUTRIENTS FOR A FEW PLANTS.

8. HOW DO LIVING THINGS AFFECT SOIL? SOME SOIL ORGANISMS MAKE HUMUS AND OTHERS MIX THE SOIL AND MAKE SPACES IN IT FOR AIR AND WATER. DECOMPOSERS ARE THE ORGANISMS THAT BREAK THE REMAINS OF DEAD ORGANISMS INTO SMALLER PIECES AND DIGEST THEM WITH CHEMICALS. THESE ORGANISMS INCLUDE FUNGI, BACTERIA, & WORMS. DECOMPOSERS

9. WORMS AND BURROWING MAMMALS MIX HUMUS WITH AIR AND OTHER MATERIALS IN SOIL. WORMS CAN CARRY HUMUS DOWN TO SUBSOIL AND SUBSOIL UP TO THE SURFACE. MAMMALS CAN BREAK UP HARD, COMPACTED SOIL AND MIX HUMUS WITH IT. ANIMAL WASTES CONTRIBUTE NUTRIENTS TO THE SOIL.

10. HOW CAN SOIL LOOSE ITS VALUE? SOIL IS ONE OF EARTH’S MOST VALUABLE RESOURCE BECAUSE EVERYTHING THAT LIVES ON LAND DEPENDS ON SOIL FOR FOOD. LESS THAN ONE-EIGHTH OF THE LAND HAS SOILS THAT ARE WELL SUITED FOR FARMING. IT CAN TAKE HUNDREDS OF YEARS FOR JUST A FEW CENTIMETERS OF SOIL TO FORM.

11. LOSS OF VALUE SOIL CAN BE DAMAGED WHEN IT LOSES ITS FERTILITY THROUGH LOSS OF MOISTURE AND NUTRIENTS. PLANT COVER CAN PROTECT SOIL FROM EROSION BY BREAKING THE FORCE OF FALLING RAIN AND BY ROOTS HOLDING THE SOIL TOGETHER. U.S. DUST BOWL OF 1930'S