DO NOW What is a PHYSICAL change What

* DO NOW: *What is a PHYSICAL change? *What is a CHEMICAL change?

Weathering- the process that breaks down rocks into smaller fragments- resulting in soil. Rates of weathering are affected by: 1. Surface area-when more is exposed, more weathering occurs.

Rates of weathering are affected by 2. Rock composition- less resistant rocks weather faster.

Rates of weathering are affected by 3. CLIMATE- rocks weather (chemically) faster in hot humid climates Sinkholes in Guatamala

TYPES OF WEATHERING 1. Mechanical Weathering- (disintegration) breaks rocks without changing the chemical composition. a. Abrasion- breaking up of rocks as they rub against each other

b. Biologic activity Root wedging- roots from plants grow and break rock Have you ever tripped over a sidewalk like this?

Animals burrow creating more surface area available for weathering to affect

c. Frost wedging- water seeps into cracks in rock and expands breaking it A pot hole is an example of frost wedging

Exfoliation or upward expansionigneous intrusions (domes) are exposed and expand from lack of pressure. <- Agents of Erosion (wind, running water ri. Vers, wave action, glaciers, mass wasting) weather and move layers of sedimentary rock

2. Chemical Weathering (decomposition)- changes molecular structure of rock, making entirely different products. a. Oxidation- when oxygen unites chemically with minerals in rock (ex) rust

b. Hydration- water unites chemically with minerals in rocks – sometimes makes clay. c. Carbonation- carbon dioxide unites chemically with minerals in rocks. Carbon dioxide + water = carbonic acid which dissolves rocks! CO 2 Oh no! Slightly Acidic Rain!

d. Biologic Activity: Hey, I’m a fun guy! Lichens, mosses, fungi, and enzymes on tree roots can decompose rock

Ca. CO 3 + 2 CH 3 COOH => Ca(CH 3 COO)2 + CO 2 + H 2 O Calcium Carbonate (chalk) + Acetic Acid (vinegar) => Calcium acetate (That white stuff on the blue) + Carbon Dioxide (The bubbles you saw in the beginning of the experiment) + Water (The reason the chalk looks wet) The Great Chalk Experiment *N TICE*You can’t get something from nothing! http: //www. yteach. co. uk/page. php/resources/view_all? id=limestone_chalk_marble_rock_water_dissolution_carbonate_mortar_cement_concrete_page_1&from=search

Remember this?

"Cleopatra's Needle”: Obelisk built in 1443 BCE. It was erected first at Heliopolis, Egypt, and moved to Alexandria in 12 BCE by the Romans. Later, presented to the City of New York by the Khedive of Egypt in 1879, and erected in Central Park early in 1881. Pink granite; 69 ft. x 8 ft. 21 meters high and weighs about 180 tons. ) Hmmmm…. Why are they different?

Chemical weathering of chalk bedrock in England. Sinkholes: http: //youtu. be/t. Qvv 8 YFCGs. Y

f o t l. u g s e n i r r e a h e t r a a e s w e l v a a c C mi e ch

Infiltration happens http: //www. teachersdomain. org/asset/ket 09_vid_karst/

What is Erosion? WIND http: //youtu. be/XAYh. NHhx. N 0 A - Coastal processes gravity Rivers Glaciers The MOVEMENT of (weathered) sediment by wind, water, ice or gravity which wears away or lowers Earth’s land surfaces. *Erosion is NOT weathering!

What is the result of weathering and erosion?

A mature soil profile Sediment Transported soil- was brought by an agent of erosion. Residual soil- weathered native bedrock

What is Deposition ? Deposition is the geological process in which sediments, soil and rocks are added to a landform or land mass. +

When wind, waves, glaciers, and gravity lose carrying power, particles are dropped onto the surface of the land. When the river meets the sea= delta

When running water meets a shallower slope, it drops the heaviest particles first. Horizontal Sorting x http: //www. classzone. com/books/earth_science/terc/content/visualizations/es 0604 page 01. cfm? chapter_no=visualization

When the river meets the land= alluvial fan Why is the surrounding area so fertile?

Factors affecting deposition in still water: 1. Particle size- larger particles will settle faster. 2. Particle shape- round particles will settle faster than flat ones. 3. Particle density- higher density particles settle first. Vertical Sorting: The number of layers tells how many depositional events occurred.

http: //hmxearthscience. com/Warehouse/geology/surface_processes/animation s/settling. swf

Types of sorting

When Weathering and Erosion (-) = Deposition (+) the landscape is in DYNAMIC EQUILIBRIUM

The End! How are your notes?