High And Low Energy Environments Flashcards
(28 cards)
What is an example of a HIGH ENERGY coastline?
Saltburn to Flamborough Head- Yorkshire
(Rocky, upland are, 60km coastline)
Geology of Saltburn to Flamborough
- Flamborough Head- Southern stretch of coastline:
Large chalk headland; spectacular cliffs topped with till (deposit left behind by glaciers during Devensian glacial period); Bays+ headlands and high cliffs (varied scenery) due to differences in rock resistance.
what is the dominant wave direction and fetch length of s to f?
what about rates of erosion?
wave height?
*Dominant waves from north + northwest
*fetch over 1500km
*most exposed coast is northfacing e.g. nearest Saltburn (relieves highest inputs of wave energy)
*rates of erosion: due to differences in wave energy and geology; weak shale + clay areas rate is 0.8m p.a. and more resistant sandstones+ limestones is 0.1m p.a.
*wave height- often exceeded 4m even in summer (usually less stormy)
*high energy inputs responsible for longshore drift (North to south)- in some places sediment movement interrupted by headlands; sand and shingle accumulates forming beaches and bays (e.g Filey Bay)
Example of a bay along s to f coastline
Filey bay
Bridlington bay
What are sediment sources for s to f coastline
- cliff erosion
- only large river (the esk) enters north sea at Whitby - limited fluvial supply of sediment due to construction of weirs and reinforced banks along its course.
what are the cliffs like at Flamborough Head?
made of chalk- physically very strong; vertical cliffs typically 20-30m high, with overlying till lowered by mass movement processes to angle about 40 degrees.
what are the cliffs like between Robin Hoods Bay and Saltburn?
further north than Flamborough: higher cliffs, often with stepped profile (more varied geology)
when are steeper sloped cliffs formed?
more resistant sandstones and limestones; gentler slopes corresponding to weaker clays.
what LANDFORMS can be found at Robin Hoods bay?
high energy waves + active erosion means cliffs are retreating, leaving behind WAVE- CUT PLATFORMS.
HEADLANDS AND BAYS: discordant coastline, weaker rock retreated and more resistant rock forming headlands (limestone and chalk).
what does the prominent headland at Flamborough consist of?
CHALK
deep bays made of CLAY
what landforms have formed on these headlands from s to f?
Robin hoods bay- WAVE- CUT NOTCH
FLAMBROUGH HEAD is a large CHALK HEADLAND between FILEY and BRIDLINGTON bays
WAVE REFRACTION- wave energy concentrated of headlands that project out to north sea; weaknesses e.g. CRACKS AND JOINTS are exploited + enlarged to form caves + arches. (e.g. SELWICK’S BAY at Flamborough Head).
GREEN STACKS PINNACLE: a stack at end of headland.
over 50 GEOS along coastline (aligned to NE/ NEE dom. wind direction)
What is an example of a LOW ENERGY COASTAL ENVIRONMENT?
the Nile Delta
What is a delta?
Large areas of sediment found at mouths of rivers- deposited by rivers+ tidal currents
How do deltas form?
Sediment is deposited at a faster rate than wave/ tides can remove it.
Typically form where:
* rivers entering sea carry large loads
* low tidal range
* low energy environments on coastline (e.g. bay)
What is an ARCUATE delta?
Sufficient sediment supply available for delta to grow seawards, but wave action is strong enough to smooth leading edge - has lagoons.
* Fan/ triangle shape with rounded leading edge
How long is the RIVER NILE?
6650km
What is the Niles CATCHMENT AREA?
Over 3 million km³
Large proportion of Nile flow originates in Ethiopia + comes from summer monsoon rains- some from central Africa
The nile carries a huge sediment load despite relatively low discharge, what sediment can be found in the suspended load?
30% clay
40% silt
30% fine sand
Where does the coastal plain of the nile delta occupy?
Northern part of nile delta
What landforms/ features are found on the foreshore plain of the delta?
Lagoons, salt marshes and alluvial deposits in the depressions between dunes and bars e,g, lake manzala
What features/ landforms can be found at the sandy zone at the delta?
Dunes
Where does the delta split into two distributaries?
What has formed here?
- Cairo
- wave action in the Mediterranean redistributes sediment at front of delta - reworked sediment forms series of CURVED BARRIER BARS; closes off segments of Mediterranean sea to form LAGOONS.
where is the HOLDERNESS COAST?
coastline extending from Flamborough Head to Spurn point (a spit)
GEOLOGY at HOLDERNESS
SOFT BOULDER CLAY- rapidly eroded by marine processes- STRUCTURALLY WEAK so very LITTLE RESISTANCE
(sloping cliffs 5-20m high)
CHALK surrounds the boulder clay; STRONGER but has eroded along FAULT LINES+ BEDDING PLANES- resulting in erosional features such as cliffs, caves, arches, stacks
