Muir Creek Fossils
"an ideal park in jeopardy"
According to Rick Hudson, “Notable fossil
sites include the exposed seashore
west of Muir Creek, where a 15 metre
high siltstone cliff contains well-defined
marine fossils in a variety of strata, and
3 km up Muir Creek where there are fossils
in random boulders exposed in the
riverbed.
During the Neogene Period, 20 million
to 25 million years ago, there was northsouth
faulting with east-west stretching
and thinning of the crust along the
western continental coastline of North
America. The resulting volcanic activity
is associated with the uplift of the Rocky
Mountains and the Coast Mountains.
The Sooke Formation (early Neogene)
is the youngest of the Tertiary sediments,
called the Carmanah Group, that make up
the south west coast of Vancouver Island.
It overlays the older Hesquiat Formation
which comprises several thousand metres
in thickness of silty shales interspersed
with conglomerates and sandstones.
The Hesquiat Formation accumulated in
deeper waters, while the Sooke Formation
formed in shallower seas and therefore
contains many fossils.
The Carmanah Group sediments show
as a very narrow strip along the south
west edge of Vancouver Island, stretching
from the Sooke Basin to Nootka Sound.
Nowhere are they extensive, and seldom
are they accessible. The Sooke Formation
is, at most, a few hundred metres thick
and comprises conglomerate and finegrained
silts, with the fossilized remains
of diverse inshore fauna including
gastropods, bivalves, barnacles and also
the fossil bones and teeth of marine
mammals.
The remnants of three different extinct
marine mammals have been identified
in this youngest of the Island’s fossil
bearing sediments: a partial skull of the
primitive whale, Chonecetus; teeth of the
desmostylian, Cornwallius; and a molar
in a partial lower jaw that is similar to the
jaw of the Kolponomos—a large, bearlike
carnivore. The jaw was found near
the mouth of Muir Creek. Desmostylians
were a group of amphibious quadrupeds
related to elephants and manatees.
Upstream about 3 km is the first showing
of fossils and of sandstone with fossil
shells. Beyond the remains of the old logging
bridge, accessible from either side of
the creek via old logging roads, there is
fossilized and partially fossilized wood.
This fossil material is usually encased in
the conglomerate rock that is common in
the upper reaches of Muir Creek. These
conglomerates form dramatic, undercut
cliffs and caves along the creek bed. The
fossilized wood is estimated to be 60
million years old. Poorly preserved and
carbonized remains of beech, hickory,
laurel, magnolia, and oak are found along
with the remains of spruce and willow.”