Physical Weathering

Exfoliation -- jointing caused by pressure release due to erosion of overlying rock 

• Exfoliation diagram -- diagram showing weathering due to pressure release
• Exfoliation -- jointing due to pressure release, North Cascades Highway, Washington
• Exfoliation -- onion-skin jointing due to pressure release, Yosemite National Park, CA
• Exfoliation -- pressure-release jointing subparallel to canyon walls, North Creek, NY

Frost wedging or riving -- due to expansion of water on freezing

• Frost wedging -- diagram showing breaking of rock as water freezes in joints and cracks
• Frost wedging -- above Coleman Glacier, Mt. Baker, WA
• Frost wedging -- top of Ben Nevis, Scotland

Spheroidal weathering -- due to corners and edges of joint blocks weathering more rapidly than faces

• Diagram of spheroidal weathering
• Spheroidal weathering of basalt --  near Dry Falls Dam, Washington
• Spherodal weathering of basalt close-up -- near Dry Falls Dam, Washington

Salt crystallization (cavernous weathering) -- due to growth of salt crystals in rock pores and cracks

• Salt efflorescence on desert floor -- Mojave Desert, CA
• Cavernous weathering close-up -- Chocolate Mtns., Arizona
• Cavernous weathering -- Chocolate Mtns., Arizona

Granular disintegration (grusification) -- due to expansion of biotite grains on slight chemical weathering

• Granular disintegration of granite cobble in 10,000 year old glacial till -- near Sumas, Washington
• Granular disintegration of biotite -rich diorite -- can be dug apart with a knife! Medford, Massachusetts
• Residual granite blocks exposed in in roadcut -- Sierra Nevada, CA
• Granite tor -- formed by erosion of weathered (grusified) granite, Pikes Peak, Colorado
• Granite residual boulders -- typical weathering of granite, near Bishop, CA
• Weathered granite outcrops -- typical weathering of granite, Mojave Desert, CA
• Hills of weathered granite -- typical weathering of granite, Sudan

Expansion and shrinking of clays on wetting and drying

• Rounded clay cobble shattered in place -- Bull Creek, Humboldt Co., CA  

Other mechanisms

• Thermal shock -- spalling of surface of granite boulder due to forest fire, San Gabriel Mtns., CA
• Wedging by tree roots -- Purgatory Canyon, Massachusetts

Chemical Weathering

Solution

• Solution rills in limestone -- Nevada
• Joints and small pits enlarged by solution -- Inishmore, Ireland
• Joints enlarged by solution -- Inishmore, Ireland
• Cave formation diagram
• Limestone cave -- Carlsbad Caverns, New Mexico
• Karst features diagram -- diagram showing features of a solution-dominated (karst) landscape 
• Disappearing stream -- karst topography: stream disappearing into sinkhole
• Sinkholes above caves -- Colorado
• Sinkhole -- sacred well of Chichen Itza, Mexico: a large sinkhole in limestone
• Winters Park sinkhole -- this sinkhole swallowed up a car dealership in 1981. Winters Park, Florida
• Karst topography -- sinkholes near Bowling Green, Kentucky
• Karst topography -- cone karst near Arecibo, Puerto Rico
• Karst topography -- tower karst, Guilin, China
• Karst topography -- tower karst, near Guilin, China
• Karst topography -- topographic map showing solutional topography 

Soils and Soil Formation

• Soil horizons -- diagram
• Thin young soil on exfoliated granite -- Lynches River, South Carolina 
• Deeply weathered granite (saprolite) showing B and C horizons -- Athens, Georgia
• Weathered granite below C horizon -- note clay seams developing along joints. Athens, Georgia

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