COASTS Bk5 - Sea Level Change Flashcards
What are the 3 milankovitch cycles?
- Eccentricity
- circular to elliptical orbit
- every 100,000 years - Obliquity
- axial tilt spins off its axis (day and night)
- every 41,000 years
- determines seasons - Precession
- wobble of the axis
- every 26,000 years
- responsible for the timings of the seasons
What is solar activity?
Presence of sunspots (maximum = more heat and larger explosions > larger flares)
- 11 year cycle
What is volcanic activity?
- global dimming > volcanic ash blocks out the sun (short term)
- finer droplets convert into sulphuric acid and reflect radiation (long term) > volcanic winter
What is ecstatic sea level change?
Variations in relative sea level resulting from changes in the amount of liquid water entering the oceans (GLOBAL ASPECT)
What is isostatic sea level change?
Variation in relative sea level associated with changes in the buoyancy if the land e.g. readjustment from the last ice age (LOCAL ASPECT)
What are the steps of isostatic sea level change?
- Colder climate > ice store > global sea levels fall
- Weight of ice causes land to sink > local scale isostatic
- Climate warms and ice melts > sea level rise (submergent features)
- Isostatic readjustment (ecstatic emergent features)
Evidence of changing temps historically?
- Ice stores
- Tree rings
- Pollen levels + types
What is an emergent coast?
A coastline exhibiting features associated with falling sea levels
What is a submergent coast?
A coastline exhibiting features associated with rising sea levels
What is isostatic rebound?
When large ice sheets cover the ground, weighs it down and makes it sink, when the ice melts, the land begins to rise again
What are emergent landforms? (2)
Appear towards the end of an ice age
- features of coastal erosion appear as they were below sea level
- raised beaches
- relict cliffs
What are raised beaches?
Marine platform / terrace (gently sloping continental shelf)
- areas of former wave cut notches
What are relict cliffs?
- cliffs above raised beaches
What are submergent features? (3)
Features of ecstatic sea level rise
- rias
- fjords
- dalmation coasts
What are rias?
- drowned by river valleys
- tree like pattern
- overtime will fill up with fluvial sediment
What are fjords?
- drowned U shape valleys (glacial trough)
- processes of glacial V>U and sea levels rise
What are dalmation coasts?
- floods where valley’s lie parallel to each other (look like islands)
