Subglacial Lakes

Adrienne is exploring East Antarctica!!!!

She heard there was a lake in the area and she has been looking for it everywhere!

I hope you can help her find it!

She is fascinated by lakes!

Maybe it is because she comes from Ohio where there are well over 1000 lakes!

OR maybe its because she likes to snorkel?

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OR maybe it is because she likes to swim?

Yes that’s Adrienne swimming in a hole cut into the Ross Ice Shelf in Antarctica. An ice shelf is a thick plate of floating ice that forms where a glacier flows off the land.

credit: YoYo' Johnson for the Ice Stories Project, (c) Exploratorium, www.exploratorium.edu

From what you can see, how thick, from top to bottom, do you think the ice is behind Adrienne? Ladder rungs are generally one foot apart.* Can you use the ladder to estimate ice thickness (height) in that area? Report your answer in cms. *(1 inch is 2.54 cm)

Did you get an answer close to 152 cms?

Let’s have fun with ice shelf math!

That would be right IF we were measuring JUST what we can see in the picture ….but with ice shelves there is more…

Can you calculate in meters the depth of the ice sheet that lies below the water surface?

~ 90% of the Ice Shelf extends underwater!

The Ross Ice Shelf is THICK! Scientists estimate it ranges from 15 to 50 meters above the water surface.

Now estimate the TOTAL ice sheet thickness in meters including both the amounts above and below the water.

Robin and Detlef are standing INSIDE the top 10% of the ice shelf !

135 to 450 meters below the ice!

10%

90%

150 to 500 meters total

Water line

And where should we be looking?

But ice shelves are not subglacial lakes. So what is a subglacial lake?

‘Sub’ + ‘Glacial’ = Subglacial

A + B = C

Simple formula right?

Sub means ‘under’

Like this submarine is ‘under’ water

Glacial refers to a glacier

or ice sheet SO we are looking for a lake underneath a glacier…hmmm

But how far underneath?

Although Adrienne did manage to swim in the Ross Sea through a cut out in the Ice Shelf, this was under 15-50 meters (49-164 ft.) of ice.

3 to 4 km

15-50 m

The lakes we are looking for are under 3 to 4 kilometers (9843-13,123 ft.) of ice in the middle of a glacier! She won’t be swimming there!

How does water stay liquid under all that ice?

Frozen lakes and ponds often have water beneath a cover of ice. Maybe you have even skated on one?

But the Antarctic subglacial lakes Adrienne is looking for are are NOT like any of the lakes you might have seen! These lakes will be hard to find since they are covered by a HUGE ice sheet that spreads over most of the Antarctic continent. This ice sheet is millions of years old, and remember it is up to 4 kms thick!

Let's try some activities and see if we can find Adrienne’s missing lakes somewhere under all that ice!

clicking on a photo below to start