Ch 16 Frq

Meghan Brockmeyer Mr. Kemp APES 3/3/09 Chapter 16 FRQ A) The building up and breaking down of our earth is caused by both internal and external processes that serve as compensating factors on the ever-changing landscape of our planet. The internal forces (the forces that “build up” our earth) that directly cause such activities as plate tectonics, convection currents, volcanoes, and island creations are heat and gravity. Both of these principles create the immense pressure and high temperatures that heat the core and give the mantle its flexibility. Through such processes plate boundaries collide, separate, and subside which in turn generate the movement of continents and ocean shelves. Additionally, internal geologic processes can determine the quantity and location of a mineral resource within the earth’s crust. The external forces that weather, erode, and change the surface features of our earth’s landscape are water, the sun, and gravity. Each of these forces contributes to the production of landforms through sediment buildup and breakdown. Erosion and Weathering are key processes within the earth’s external forces, as wind, water, and human activities move, extract, and change soil while physical, chemical, and biological forces break down rocks and minerals to be eroded. B) Mechanical and Chemical Weathering differ by the various ways in which large rock masses are broken down. In mechanical weathering, rocks are broken down

into smaller fragments many times through pressure, force, or frost-wedging. The most common example of mechanical weathering is when water collects in pores and cracks of rock, and that water expands upon freezing, splitting the rock and hence causing frost-wedging. Chemical weathering is distinguishable because it is when rocks are decomposed by chemical reactions that usually are solid and dissolved components. Frequently occurring examples of chemical weathering are when rock material reacts with oxygen, carbon dioxide, and moisture in the atmosphere, gradually softens and breaks apart. C) The processes of weathering and erosion are different in that weathering breaks down rock and erosion transports broken down and worm away materials to other places. Both process contribute to the movement and deterioration of rock as expressed in the rock cycle but the two forces are different in their approach to dislocate rocks from their original state or location. Weathering is specifically powered by mechanical or chemical processes that overturn rocks, sediments and soil. Erosion mostly displaces loosened materials such as rocks and soil through wind and water. D) Three fundamental processes of the rock cycle are: a. Melting- Process in which rocks undergo intense amounts of heat and pressure, where they either turn to magma, cool, and form igneous rocks, or (if they are already igneous) directly undergo direct heat and pressure and become metamorphic rock (Granite, Pumice, Basalt). b. Erosion- Process in which igneous or metamorphic rocks weather, erode, and break down, eventually going through transpiration and deposition to

become sedimentary rock (ex. Slat, Sandstone, Limestone). c. Metamorphism- Process in which rocks undergo EXTERNAL heat, pressure, and stress and are compacted enough so that they become metamorphic rock (ex. Slate, Marble, Quartz).