A
Valley
is
a
landform,
typically
at
least
a
few
square
miles
(kilometers)
but
often
hundreds
or
even
thousands
of
square
miles
(kilometers),
surrounded
by
higher
areas,
mountains,
or
hills.
Valleys
are
formed
by
numerous
geographical
processes,
and
can
result
in
'Glacial
Valleys'
formed
millions
of
years
ago
by
Glaciers,
or
Rift
Valleys,
formed
by
the
expansion
of
the
Earths
crust
due
to
activitiy
beneath
the
Earths
surface.
Valleys
are
most
commonly
formed
by
fluvial
activity
(the
action
of
running
water),
which
erodes
the
landscape.
Famous
valleys
include:
Photographs,
illustrations
and
clipart
at
Classroom
ClipArt.com