sedimentary rocks and environments

What is bedding?

Layers of sediment deposited over time

What does cross-bedding indicate?

Wind or water current direction

Ripple marks indicate what?

Shallow water or wind action

What causes graded bedding?

Slowing water currents depositing large grains first

What environment do mud cracks show?

Drying of wet sediment (tidal flats, lakes)

What do fossils in sedimentary rocks indicate?

Past life and depositional environment

What is stratification?

Visible layering in sedimentary rocks

What is Banded Iron Formation and environment?

Chemical sedimentary rock with alternating layers of iron oxides and silica. Environment: Ancient ocean basins with fluctuating oxygen levels (Precambrian)

Category of breccia, identifying feature, environment

Clastic sedimentary, angular fragments, Near-source deposits like landslides or alluvial fans

What is bauxite and environment?

Aluminum-rich chemical sedimentary rock, Intense tropical weathering of aluminum-rich rocks

Composition of chert/flint, category, environment

Microcrystalline quartz (SiO₂), chemical or biochemical sedimentary, deep marine silica-rich environments

Conglomerate category, grain type, environment

Clastic, rounded pebbles and cobbles, high-energy rivers and beaches

Dolostone composition, how it forms, environment

Clastic, made of dolomite material, forms from alteration of limestone by magnesium-rich fluids, shallow marine

Rock Salt (Halite) category and environment

Chemical evaporite, evaporating seas or salt lakes

Rock Gypsum category and environment

Chemical evaporite, arid basins with evaporating water

Shale grain size, environment

clay-sized particles, Low-energy environments like deep ocean, lakes, lagoons

Anthracite

• Highest grade coal

• Highest carbon content

• Formed from intense pressure/heat on older coal

• Swampy, plant-rich environments

Bituminous coal

• Medium grade

• Most common coal used for energy

• Swampy, plant-rich environments

Lignite

• Lowest grade

• Least compacted, brown coal

• Swampy, plant-rich environments

Chalk, environment

Soft limestone made of microscopic shells, warm shallow marine

Coquina, environment

Limestone made of loosely cemented shell fragments, high-energy beach environments

Fossil limestone defining feature, environment

Visible fossil fragments, marine

Oolitic limestone composition, environment

Small rounded calcite grains (ooids), Shallow, wave-agitated tropical seas

How travertine forms, environment

Precipitation of calcite from springs or caves, Hot springs and cave systems

Arkose composition, what does it indicate

Feldspar-rich sandstone, rapid deposition near granite source

Quartz sandstone composition, environment

Mostly quartz grains, Beaches and deserts