Glacial Flour Makes Some Lakes Turquoise

As
glaciers
slowly
move
over
land,
their
motion
grinds
up
rock
into
dust.
These
particles
form
what’s
known
as

glacial
flour,
or
rock
flour.
Gravity
and
the
sheer
weight
of

glaciers
causes
them
to
move
slowly
downhill.
As
these
large
masses
of

ice
shift,
friction
scours
the
underlying
rock
and
ground,
creating
fine
dust.

Glacial
flour
absorb
longer
wave
colors

Eventually,
much
of
this
dust
ends
up
traveling
along
with

glacial
meltwater
into
lakes.
Since
the
particles
that
make
up
glacial
flour
are
so
fine,
they
tend
to
accumulate
in
the
upper
layer
of
the
lakes.
Known
as
the
benthic
zone,
this
is
the
layer
of
a
lake
where
light
penetrates.
As
sunlight
reflects
off
the
glacial
flour
particles,
red,
orange,
and
yellow
(longer
wave
colors)
in
the
light
spectrum
is
absorbed.
Only
green
and
blue
are
reflected
(shorter
wave
colors)
–
when
these
two
mix
they
form
the

turquoise
color
seen
in
glacial
lakes
on
satellite
imagery.

Tustumena
Lake

Tustumena
Lake,
located
on
the
Kenai
Peninsula,
is
Alaska’s
8th
largest
lake.
Originating
from
the
Harding
Icefield,
Tustumena
Glacier
feeds
glacial
flour
in
Tustumena
Lake,
giving
this
deep
lake
its
turquoise
color
as
seen
on
this

Landsat
8
satellite
image
taken
on
September
20,
2024.

Turquoise
lakes
on
South
Island
in
New
Zealand

Lake
Pukaki,
Lake
Tekapo,
Lake
Ohau,
and
Lake
Benmore
on
South
Island
in
New
Zealand
are
also
known
for
their
turquoise
hues.
These
alpine
lakes
are
fed
by
rivers
that
bring
glacial
flour
runoff.
Lake
Tekapo
is
fed
by
meltwater
from
the
Classen,
Gray,
and
Godley
glaciers
that
empty
into
Godley
River.
Lake
Pukaki
receives
runoff
from
the
Tasman
and
Hooker
glaciers
via
the
Tasman
River.

Go to Source
Author: Caitlin Dempsey