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Oxidation. Oxygen combines with iron-bearing silicate minerals causing "rusting" biotite Iron oxides are red, orange, or brown in color . Hydrolysis – affected by H 2 0. Feldspar alters to clay Feldspars = stable at high temperatures and pressures
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Oxidation • Oxygen combines with iron-bearing silicate minerals causing "rusting" • biotite • Iron oxides are red, orange, or brown in color
Hydrolysis – affected by H20 • Feldspar alters to clay • Feldspars = stable at high temperatures and pressures • Claysare stable under conditions at the Earth's surface • Quartz turns to sand
Biological Action • Lichens, fungi, and other micro-organisms • Chemically and physically change rock
Spheroidal Weathering • chemical weathering of jointed rocks. • weather to form spherical shapes
Factors Affecting Weathering *Surface Area Texture Temperature Humidity Plant growth Topography Time Mineral Content Least stable Olivine Ca plagioclase feldspar Pyroxene Amphibole Biotite Na plagioclase feldspar Potassium feldspar Muscovite Quartz Most stable
Factors Affecting Weathering Surface Area – Most important • Smaller particles, more surface area • Examples • Crushed ice cools faster • Granulated sugar dissolves faster • More exposed rocks weather more
Factors Affecting Weathering • Type of material – both are from 1780’s; one is slate, the other is marble. Which is which? Why is there a difference?
Erosion • Movement / transportation • Wind, water, glacier • Mast Wasting - Movement of large amounts of material downhill under gravity • Creep • Mudflows • Slump • Rockfalls • Landfalls • Avalanches
What happens to Granite? Weathering 1. The feldspars undergo hydrolysis to form ________ and Na and K ions The Na and K ions removed by leaching. 2. The biotite & amphibole will undergo hydrolysis to form clay, and oxidation to form _________. 3. The quartz (and muscovite, if present) will remain as residual minerals because they are very resistant to weathering. They get smaller to make ________. Granite contains Na Plagioclase feldspar, K feldspar, Quartz • Lesser amounts of biotite, amphibole, or muscovite Weathered rock fragments are one of the constituents of soil – our next topic.
Erosion is Movement of Sediment! • This process, known as Erosion, is gradually wearing down the surface of the earth. • Erosionis the process by which weathered rock and soil (sediment) are moved from one place to another. • Erosion carves the Earth's surface creating canyons, gorges, and even beaches. What do you think has caused this rock to look this way?
Wind Erosion • As the wind blows it picks up small particles of sand/sediment and blasts large rocks with the abrasive particles, cutting and shaping the rock. • The intensity of wind erosion is determined by: • Sum (amount) • Speed • Slope • Surface
Wind Erosion Creates sand dunes Greatest impact in deserts Removes fertile topsoil
Water Causes Erosion • runoff, rivers and, streams Creates MOST of the changes in the Earth's landscape!
Water causes Erosion When rain falls to the Earth it can evaporate, sink into the ground, or flow over the land as Runoff. When it flows over land, erosion occurs. Runoff picks up pieces of rock and "runs" downhill cutting tiny grooves (called rills) into the land. Rivers and streams are a constant flow of runoff- they constantly weather and erode!
Water causes Erosion How much erosion takes place is determined by the: • Sum (amount) • Slope • Speed • Surface Can you act increasing and decreasing the four S’s?
Ice Causes Erosion Glaciers wear down the landscape; by picking up and carrying debris that moves across the land along with the ice.
Ice Causes Erosion Glaciers can pick up and carry sediment that ranges in size from sand grains to boulders bigger than houses. Moving like a conveyor belt and a bulldozer, a single glacier can move millions of tons of material!
Ice Causes Erosion How much erosion takes place is determined by the: • **Sum (Glaciers are massive!) • Slope • Speed • Surface
Gravity causes erosion Creep, Slump, Landslides, Mudslides, and Avalanches. Slower Faster These are examples of mass movement (or called mass wasting) landslide clip.mpeg
Gravity causes Erosion How much erosion takes place is determined by the: • Sum • **Slope • Speed • **Surface
Deposition Rock particles that are picked up and transported during erosion will ultimately be deposited somewhere else Deposition is the process by which sediments (small particles of rock) are laid down in new locations. • Together, Erosion and Deposition build new landforms. • Deltas • Canyons • Meanders • Floodplains
Delta Where rivers meet the ocean is called the mouth of the river. Soil and dirt carried by these rivers is deposited at the mouth, and new land is formed. The new, soil-rich land is known as a Delta
Canyons This simple animation provides you with a visualization of how the Colorado River has "downcut" into the rock layers of the Grand Canyon. How long it took to carve the Grand Canyon is debated bygeologists. Some estimates are between 6 and 8million years, which is very recent by comparison. Canyons are large valleys created by a river or stream.
Meanders Meandering streams wander side to side as they constantly seek out the lowest elevation. This constant motion creates a series of S-shaped “loops”.
Meanders Stream Velocity varies from one side to the other side of the “S”, resulting in erosion in some places and deposition of sediments in others.
Floodplains • Floodplains form along the banks of mid-order streams and larger rivers. • These are low-lying areas along the sides of a river channel that have regular times of heavy waterflow to cause the river to spill over and flood the land.
