Depositional Environments

Depositional Environments

1. Continental

   • Alluvial Fan
     • Poorly sorted conglomerate from debris flows and sandstone- and conglomerate-filled channels Types of rocks: Breccia, conglomerate, arkose, greywacke Physical Characteristics:  gravel to clay; angular; poorly sorted Chemical Characteristics: terrigenous; brown Inorganic Sed Structures: graded bedding; cross strat Biogenic Sed Structures: n/a Fossils: n/a
   • Sand Dune
     • Well sorted, well rounded sandstone with large scale cross-bedding
   • Lacustrine
     • Type of rocks: mudstone/shale, limestone, rock gypsum, rock salt Physical Characteristics: Silt, sand, clay; moderately to well sorted Chemical Characteristics:  Terrigenous; organic; carbonate evaporites Tan, brown, grey, green, black Inorganic Sed Structures: mudcracks; laminations; graded bedding; symmetrical ripple marks; raindrop imprints Biogenic Sed Structures: tracks, trails, burrows, stromatolites (rare) Fossils: Freshwater shells, bones, fish, land plants 
   • Glacial
     • Type of rock: Breccia, tillite Physical Characteristics: Clay to gravel, boulders; angular poorly sorted; polished and/or striated rocks Chemical Characteristics: Terrigenous Inorganic Sed Structures: Bedding Biogenic Sed Structures: n/a Fossils: n/a
     • Outwash
       • Much like braided stream deposits
     • Moraines
       • Unsorted, non-stratified deposits of sand and gravel
   • Fluvial
     • Shoestring geometry Point bar deposits Type of rocks: Conglomerate, breccia, sandstone, mudstone/shale Physical Characteristics: Gravel sized to clay; rounded to angular; poorly sorted to well sorted Chemical Characteristics: Terrigenous; brown, red Inorganic Sed Structures: Graded bedding, mud cracks, raindrop imprints, assymetric ripples, scour marks/flute casts, cross-strat Biogenic Sed Structures: Tracks, trails, burrows Fossils  Bones, land plants, freshwater shells
     • Braided stream
       • Mostly horizontally bedded conglomerate and cross-bedded sandstone; mudrocks not common
     • Meandering stream
       • Mostly mudrocks deposited on floodplains; subordinate but distinctive lenticular sandstones deposited in point bars

2. Transitional

   • Beach
   • Delta
   • Tidal Flat
   • Barrier Island
   • Lagoon

3. Marine

   • Continental Shelf
   • Submarine Fan
   • Organic Reef
   • Deep Marine Basin