Sedimentary Environments Flashcards
Why do we care about the sedimentary rock environments of the past?
Tells us about Earth’s past surface
What are the three main groups of clastic sedimentary rocks?
Conglomerate and breccia
Sandstone
Siltstone and shale
What are the three main groups of chemical sedimentary rocks?
Limestone
Coal
Evaporites
Made of blocks and pebbles, hard to erode. These form steep cliffs
Conglomerate and breccia
Made of quartz sand, also hard to erode. These form cliffs
Sandstone
Made of fine mud and clay, easy to erode. These form gentle slopes.
Siltstone and shale
Jagged blocks of sediment = very short transport distance
Breccia (high energy)
Rounded pebbles = more movement during transport
Conglomerate: high energy
Poorly sorted, jagged, and dirty sand: some transport by…..
River or delta channels (sandstone moderate energy)
Well sorted, rounded, and clean sand: lots of transport in…
Sand bars and along beaches (sandstone moderate energy)
Very well-sorted, fine-grained, and frosted sand: lots of transport by the wind in…
Deserts (sandstone moderate energy)
Shale or silt with sea-shells:
Shallow marine shelf (siltstone/shale: low energy)
Shale or silt with plant fossils or nearby coal layers:
river floodplain (siltstone/shale: low energy)
Shale or silt with a mixture of sea shells and plant fossils:
delta bays (between channels) (siltstone/shale: low energy)
Made of calcite shells, forms cliffs in dry climates, but dissolves and forms slopes in wet ones
Limestone
