sea level change Flashcards
what is eustatic sea level change
the rise or lowering of sea levels due to a change in the volume of water in the oceans
what is isostatic sea level change
the rise or lowering of sea levels due to a regional uplift or subsidence of the land, land moves relative to sea
how will land moving vertically down affect sea levels
sea levels will significantly decrease
what are the types of eustatic sea level change
-thermal expansion of water
-glacio eustatic sea level rise
what is thermal expansion of water
as global temps rise, the oceans get hotter. water will expand by 4%
what is glacio eustatic sea level rise
as world temps get hotter, big ice sheets start to melt, releasing huge amounts of trapped water into the oceans causing a rise in the sea level
what is an example of glacio eustatic sea level rise
Antarctica is losing ice mass (melting) at an average rate of about 150 billion tons per year,
what are the types of isostatic sea level change
-isostatic adjustment/rebound
-subsidence
-orogeny
what is isostatic rebound
as ice sheets melt over thousands of years time, it releases pressure on the land and over a very long time the land slowly starts to move back up.
what is subsidence
when land becomes water logged, it collapses. this causes a decrease in the relief of land
how can volcanoes affect the relief of land
repeating lava flows can build up land as they cool down
what is orogeny
new mountains forming through the collision of two plates. such as the oceanic and continental plates moving together
how has sea level changed in the past 10,000 years
during the last ice age 110,000-12,000 years ago,sea level was 130m lower than present. in the last 10,000 years ice sheets have started to melt. global sea level is currently rising at about 2mm a year due to thermal expansion of water, global temps have risen by 1.08 degrees between 1900 and 2016.
how has sea level changed in the past 10,000 years
during the last ice age 110,000-12,000 years ago,sea level was 130m lower than present. in the last 10,000 years ice sheets have started to melt. global sea level is currently rising at about 2mm a year due to thermal expansion of water, global temps have risen by 1.08 degrees between 1900 and 2016.
how many mm a year is sea level rise expected to be by 2100
8-15mm a year
what impacts do humans have on sea level rise
-greenhouse gas emissions have caused thermal expansion of water
what occurs quicker, eustatic or isostatic
eustatic
what are some differences between eustatic and isostatic sea level change
-isostatic takes a longer time
-eustatic is global
-isostatic is regional
-eustatic the sea changes in relation to land
-iostatic is where land changes in relation to sea
what does submergence mean
when sea levels rise and land is flooded/drowned. also known as marine transgression
what landforms appear due to marine transgression
-rias
-fjord
-dalmation coastline
what is a ria and how is it formed
A ria is a valley that has been partially submerged by water near a coastline, formed by a rise in sea level
what is the long and cross profile of a ria like
wide and deep at the mouth and becomes narrower and shallower as it gets further inland
what is an example of a ria
kingsbridgeestuary devon
what is a fjord
a drowned glacial valley (u-shaped valley)
how are fjords formed
-during cold periods snow and ice build up to form a glacier
-the glacier flows down slope under the force of gravity (basal slippage)
-as the glacier moves it grinds subglacial sediment into the rock below it
-forms a u shaped valley
-warmer conditions causwe glacier to melt and leave behind the u shaped valley
-thermal expansion of water has causes a rise in sea level and u shaped valley is flooded
-entrance to fjord is shallow, called a threshold
what is sublimation
the conversion of a substance from solid to gas without being a liquid
what is an example of a fjord
the sognefjoden fjord in norway
how long is the sognefjoden fjord
over 300km long
what is the entrance to a fjord called and why it it shallow
a threshold, its shallow because it has a raised bit of land formed by deposition of material by the glaacier
what is a dalmation coastline
a series of elongated islands that sit parallel to the coastline, result of sea level rise
hat sort of coastline is needed for a Dalmatian coastline ti form
a concordant coastline
