Gowganda conglomerate, sedimentary
rock,
found
in
Elliot
Lake,
middle
Precambrian,
Huronian supergroup
rocks,
2,200
–
2,450
million
years
ago.
Gowganda conglomerate
is
a
very
striking
material.
Generally
it
consists
of
rounded
boulders
and
pebbles
of
pink
granite
and
other
rocks
in
a
fine
grained
grey
mud.
The
rock
has
a
uniform
hardness,
breaking
across
the
boulders
and
grey
mud
evenly.
Geologists
think
that
the
gowganda
conglomerate
is
a
tillite,
formed
by
glaciation
during
the
middle
Precambrian.
In
some
areas
dropped
stones
are
found
finely
layered
(varved)
clays.
This
is
the
evidence
for
thinking
that
icebergs
dropped
the
stones
into
the
mud.
Sometimes
pieces
of
gowganda
conglomerate
can
be
found
in
gravel
pits
and
at
beaches
along
Lake
Huron
and
throughout
southern
Ontario.
This
material
was
collected
by
glacial
ice
in
the
area
below
during
the
Pleistocene
Epoch,
and
transported
to
the
south.
