change in sea level - not finished

what is sea level change?

is the change in height of the sea relative to the height of the land.

what are sea level changes usually associated with?

tectonic events or glacial/inter-glacial periods

word to describe change in height of land?

isostatic

what happens to the land during periods of glaciation

weight (glaciers a mile thick, 180,000 years ago) of ice causes the land to sink - isostatic depression

a relatively slow process

what happens to land during interglacial periods?

land will rise again - isostatic uplift

word to describe the change in volume of water in the sea?

eustatic

since the last ice age 18,000 years ago sea level has risen by 120m as ice caps have retreated

by 2100 expected to rise by a further metre as global warming causes more ice caps to melt and water molecules to expand

sea level is currently rising eustatically by 1-2mm a year

are isostatic or eustatic changes quicker?

eustatic

glacial period - ice locked up

inter-glacial - ice melts

this responds quicker than land

when are features of submergence formed?

when sea levels rise and ‘drown’ existing features

3 features of submergence?

Ria, fjord, Fjard

Ria

deep, sunken river valley drowned by sea, which forms funnel shaped branching inlets, decreasing in depth and width inland

e.g. Solva, Milford Haven (largest ria estuary in Wales)

Fjord

Narrow, lengthened and steep marine trough which results from the invasion by the sea of a U-shaped valley dug by a glacier.

e.g. Sogne, west coast of Norway

It is an inlet of the sea extending far inland between precipitate (minerals precipitate from a solution) rock formations. the walls of rock enclosing the fjord continue far below the surface of the water.

the mouth of the fjord is usually shallow. The greatest depth exist at locations far from the ocean

Fjard

drowned glacial lowlands

occur in glaciated low relief areas like western Scotland and N/W Ireland

e.g. Bantry Bay, Ireland

when do features of emergence form?

when sea levels fall and expose existing features, becoming relict features