Geologic Features and Processes Gallery
Special Galleries: Sedimentary Structures, Concretions
AlluviumYoung fresh waterborne sediment found alongside streams.
AmygdulesMineral-filled bubbles in frozen lava.
AnticlineFolded rocks with the sides sloping away from each other.
AvulsionRiverbeds shift, ignoring our political boundaries.
Basalt ColumnsHexagonal jointing makes pencil-stacks in cooling lava.
BeddingThe most common feature of sedimentary rocks.
BioturbationA desert anthill illustrates an important geologic process.
Black SandBlack sand is rare except in places like Hawaii.
BlocksBlocks are boulders being born from solid rock.
BoudinageFolding and stretching creates these sausage-y forms.
Braided StreamAlso called an anastomosing stream.
Channel CastThe fossil of a sand flow cutting into mud.
ConcretionsRounded rocks bound with mineral cement in curious shapes.
Contact MetamorphismLava has baked mud into brick-red rock.
Convolute LaminationSquirmy shapes in sedimentary rock beds.
DendriteNot fossils, but treelike mineral growths.
Desert PavementDeserts generally have a surface of stones like this.
Desert VarnishA close-up and explanation of this dark rock coating.
DikesExamples of sandstone and basalt intrusions.
Drag FoldRock layers bent along a fault.
ExfoliationThis erosional process sends slabs down a granite slope.
FiammeFlamelike signs of extreme volcanic conditions.
Flame StructureWisps of clay drawn up into a heavy overflow.
Flute CastsTracks left in sedimentary rocks by fast waters.
FoldingSan Francisco's chocolate chert shows its wrinkles in an outcrop.
Foreset BedsSedimentary bedding laid down on a slope.
Gas-Escape StructuresThey look similar to raindrop impressions.
Geopetal StructureA sign of the ancient horizontal direction.
GeyserEveryone's favorite geologic personality.
Graded BeddingA reliable indicator of up and down.
GrusGranite weathers into this clean natural gravel.
HornitoSpurting lava builds little cones resembling old-fashioned ovens.
Hummocky Cross-BeddingStony evidence of sand-sweeping storms.
ImbricationA stacking pattern that points to ancient currents.
JointingOrganized cracks march in sets up a Sierra Nevada streambed.
Kink FoldsSharply creased shale beds in a Canadian roadcut.
KnockersA local name for the peculiar rocky knobs of mélange country.
LaminationA finely layered form of sedimentary structure shown in siltstone.
Landslide Picture GalleryExamples of several landslide types.
Lava PillowsCommon on the seafloor, here exposed on land.
Load CastsFootprints in mud of a seafloor avalanche.
MudcracksA stony mosaic documents a dry period in a wet place.
Pele's HairWind stretches hot lava into blonde fibers.
Retrograde MetamorphismHow a former garnet schist lost its garnets.
RipplesSigns of an ancient, gentle limestone sea.
Rip-Up ClastsSigns of an ancient seafloor avalanche.
Scour-and-Fill StructuresTypical signs of turbidites.
SillAn igneous intrusion within the beds of another rock.
SlickensideThe "fault mirror" or polished surface of a San Francisco fault.
Spheroidal WeatheringThis near-surface process makes a basalt bulls-eye.
Stromatolitic StructureFossils of ancient bacterial mats.
SynclineA spectacular giant fold in the Canadian Arctic.
TafoniCavernous weathering turns solid rock into honeycomb.
TalusCall this rock debris scree, too, if you like.
Thrust FaultIllustrated by the spectacular Keystone thrust of Nevada.
VeinA crack with a story.
Special Gallery: Lava Pillows
Other galleries:
Fossils
Glaciers and Ice
Landforms
Minerals
Rocks
Geology and Society
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