This rock at the base of the cliff, just west of where the trail
reaches the beach is highly representative of how mixed up this sequence
of rocks actually is. Here the pink rock on the right of the boulder
is chert, the green in the center is volcanic material and the black on
the left is shale. All mushed together, rather like one of those
buildings that has been demolished by implosion and the walls, floors and
plumbing are all lying there as a massive pile of rubble. The collision
of the old sea floor and the North American continent caused a lot of disruption
of these rocks. Rocks that have this character are what geologists
call melange and we will be observing some of the characteristics of this
type of rock association.
More on melange |
