Clastic Shorelines Flashcards
Name 7 Transitional environments?
marsh,swamp chenier estuary tidal flat Beach Barrier bars Lagoon
grain size decreases with water depth in coastal depositional environments: T or F?
TRUE
Where do coastal depositional systems form?
in proximity to shorelines
What are the 3 fluid flow transport methods and deposition for coastal depositional systems?
- Fluvial input
- Wave action
- Current action
Define progradation and retrogradation
progradation: sediment deposition that build forward ocean-wards
retrogradation: sediment deposition that build backwards land-ward
What is a swamp?
shallow lake, water stagnant or contain very feeble current, filled with vegetation, bordered by trees
What is found in-situ in a swamp environment?
Peat and 3 grades of coal (lignite, bituminous, anthracite)
What are Cheniers?
Exposed beach ridges, composed of sand or shells within marshes on a coastal plain
Where are Cheniers formed?
near estuaries and in mudflats with low wave energy but effective long shore currents
Example of a chenier?
St Phillips Island, SC
What is an estuary?
semi enclosed body of water, in which fresh water mixes with sea water. Typically, old river valleys that have been drowned by marine transgression.
What is the facies of an estuary system?
extremely complex mix of lithology’s and sedimentary structures.
Do sediments coarsen upward or downward from marine shales in an estuary system?
coarsen upward
Are the sand bodies in an estuary system perpendicular or parallel to a basin margin?
perpendicular
What are tidal flats?
marshy or muddy land areas which are covered and uncovered by the rise and fall of the tide in the absence of string wave action.
What two setting do tidal flats occur in?
open coast(low relief, low energy) Protected areas (high energy including bays, estuaries and fiords (glacial origin))
Where are tidal flats present?
where part of shoreline periodically covered
by seawater at high tide and then exposed at low tide.
Do most tidal flats prograde or regress seaward?
prograde (from sand to mud)
What is one of the most distinctive features of tidal flats?
herringbone cross-bedding
Tidal flats are divided into what 2 environments that control facies development?
- intertidal
2. subtidal
what is an intertidal tidal flat?
refers to the tidal flat lying between the high and low tide range.
what is a subtidal flat?
area of the tidal flats that are more likely to be preserved in the geological record.
Define shoreline, fore shore, shore face
shoreline: line of intersection of the sea with the land
fore shore: the narrow zone between the high and low tide shorelines
shoreface: the narrow zone seaward from the low tide shoreline permanently covered by water, over which sands and gravels oscillate with changing wave conditions
Define a beach
deposit of unconsolidated sediment extending landward from low tide to a change in topography such as a line of sand dunes, or the point where permanent vegetation begins
What is a lagoon?
body of shallow water, particularly one with a restricted access to the open coean
Where do lagoons occur?
landward of barriers bars and reefs within atolls
