Geologic Features and Processes Gallery
Special Galleries: Sedimentary Structures, Concretions
Alluvium—Young fresh waterborne sediment found alongside streams.
Amygdules—Mineral-filled bubbles in frozen lava.
Anticline—Folded rocks with the sides sloping away from each other.
Avulsion—Riverbeds shift, ignoring our political boundaries.
Basalt Columns—Hexagonal jointing makes pencil-stacks in cooling lava.
Bedding—The most common feature of sedimentary rocks.
Bioturbation—A desert anthill illustrates an important geologic process.
Black Sand—Black sand is rare except in places like Hawaii.
Blocks—Blocks are boulders being born from solid rock.
Boudinage—Folding and stretching creates these sausage-y forms.
Braided Stream—Also called an anastomosing stream.
Channel Cast—The fossil of a sand flow cutting into mud.
Concretions—Rounded rocks bound with mineral cement in curious shapes.
Contact Metamorphism—Lava has baked mud into brick-red rock.
Convolute Lamination—Squirmy shapes in sedimentary rock beds.
Dendrite—Not fossils, but treelike mineral growths.
Desert Pavement—Deserts generally have a surface of stones like this.
Desert Varnish—A close-up and explanation of this dark rock coating.
Dikes—Examples of sandstone and basalt intrusions.
Drag Fold—Rock layers bent along a fault.
Exfoliation—This erosional process sends slabs down a granite slope.
Fiamme—Flamelike signs of extreme volcanic conditions.
Flame Structure—Wisps of clay drawn up into a heavy overflow.
Flute Casts—Tracks left in sedimentary rocks by fast waters.
Folding—San Francisco's chocolate chert shows its wrinkles in an outcrop.
Foreset Beds—Sedimentary bedding laid down on a slope.
Gas-Escape Structures—They look similar to raindrop impressions.
Geopetal Structure—A sign of the ancient horizontal direction.
Geyser—Everyone's favorite geologic personality.
Graded Bedding—A reliable indicator of up and down.
Grus—Granite weathers into this clean natural gravel.
Hornito—Spurting lava builds little cones resembling old-fashioned ovens.
Hummocky Cross-Bedding—Stony evidence of sand-sweeping storms.
Imbrication—A stacking pattern that points to ancient currents.
Jointing—Organized cracks march in sets up a Sierra Nevada streambed.
Kink Folds—Sharply creased shale beds in a Canadian roadcut.
Knockers—A local name for the peculiar rocky knobs of mélange country.
Lamination—A finely layered form of sedimentary structure shown in siltstone.
Landslide Picture Gallery—Examples of several landslide types.
Lava Pillows—Common on the seafloor, here exposed on land.
Load Casts—Footprints in mud of a seafloor avalanche.
Mudcracks—A stony mosaic documents a dry period in a wet place.
Pele's Hair—Wind stretches hot lava into blonde fibers.
Retrograde Metamorphism—How a former garnet schist lost its garnets.
Ripples—Signs of an ancient, gentle limestone sea.
Rip-Up Clasts—Signs of an ancient seafloor avalanche.
Scour-and-Fill Structures—Typical signs of turbidites.
Sill—An igneous intrusion within the beds of another rock.
Slickenside—The "fault mirror" or polished surface of a San Francisco fault.
Spheroidal Weathering—This near-surface process makes a basalt bulls-eye.
Stromatolitic Structure—Fossils of ancient bacterial mats.
Syncline—A spectacular giant fold in the Canadian Arctic.
Tafoni—Cavernous weathering turns solid rock into honeycomb.
Talus—Call this rock debris scree, too, if you like.
Thrust Fault—Illustrated by the spectacular Keystone thrust of Nevada.
Vein—A crack with a story.
Special Gallery: Lava Pillows
Other galleries:
Fossils
Glaciers and Ice
Landforms
Minerals
Rocks
Geology and Society
Free Geologic Wallpaper Pictures
