At the La Brea Tar Pits, crude oil has been
seeping up to the surface of the earth along
cracks and fissures through the rock forming ponds
of asphalt in low-lying areas.
LaBrea-1 to enjoy a picture
Again click in
These asphalt ponds at the surface made the
area around the La Brea pits a hazardous place for
animals to roam, especially in the hot summer
months when the semi-solid asphalt turns softer
and stickier. Sometimes, leaves, dust, water etc.
would cover the asphalt obscuring it from view and
creating a trap that animals could get stuck in!
Once one animal became stuck in the tar, other
carnivores or scavengers would try to attack the
stranded animal, sometimes becoming stuck in the
asphalt themselves as well!
LaBrea-3 for a nice picture of an animal in
So, not only does the asphalt create a
dangerous place for animals where they may die,
but because the remains of dead animals sink
relatively quickly down into the asphalt where
they are completely buried, their bones are very
likely to be preserved as fossils. After the
soft parts of the animal (muscles, skin, etc.)
decay and are eaten away by bacteria that live in
the pond, the hard porous bones become
saturated with asphalt and sink into the pit,
preserving them from further decay and breakdown
that would occur if they were exposed to the
elements at the surface.
LaBrea-4 to see the bones preserved
Great question! I hope this is a satisfactory