EVIDENCE FOR ISOSTATIC AND EUSTATIC SEA LEVEL CHANGES

•What does isostatic mean?•What does eustatic mean?•Which is changing in these photos – land level or sea level?

Aerial view of the raised beach on the west coast of Arran.

Old stacks

Raised beach covered with coarse shingle.

Old cliff line

Diagram from Arrran and the Clyde Islands, Scottish Natural Heritage

Raised beaches

http://www.bbc.co.uk/scotland/education/geog/coastline/standard/physical/features/sea_level/

Sea level 13,000 years ago

Sea level 6,000 years ago

Sea

Cross section though raised beaches

RockCave

Rock platform

Beach

Raised beaches

Stack

Raised beach, Newton Point, Arran

wave-cut platform old cliff line

King’s Cave, from the Drumadoon sill

wave-cut platform

old cliff line

King’s CaveAll the caves are full of very rounded pebbles , which have the same texture as beach pebbles.

The caves also contain many marine shells, which are encrusted with lichens. They are not part of the present marine deposits.

Raised sea stack, Bute.

Raised beach

Diagram from Arrran and the Clyde Islands, Scottish Natural Heritage

Raised natural arch

Raised beach deposits are

usually made of coarse, rounded pebbles. This

deposit is cemented with iron. Godrevy Point, Cornwall

Close-up of the

Godrevy Point

deposit

Marine platformsIsland above old sea level

Penberth, Cornwall

Marine platform

River terracesThe Graded Steam

Idealised cross section

Upper reaches

Middle reaches

Lower reaches

Oblique view upstream

Terraces

Knick point

A

B

C

A

C

B

Idealised long profile

Knick points

Sea level 2

Sea level 3

Sea level 1

River

River terraces, NW Scotland

River terraces, Catacol

Drowned coast-lines

Drowned glacial trough

West coast of Norway

Fjord

Norwegian fjord

Drowned coast-linesSouth coast of Devon

ria

Drowned river valley

Ria in Cornwall

Raised coastlines Skogarfoss

Iceland

Atlantic

Old cliff line

The End

River Skoga, falling over the post-glacial cliff

THE END