Mark Wilson November 27th, 2009
SAN DIEGO, CALIFORNIA–A nice geological interlude for this Wooster geologist during a family Thanksgiving. This afternoon we visited Los Peñasquitos (meaning little cliffs) Canyon Preserve in San Diego County. We walked about two miles along a trail to an exposure of Jurassic metaconglomerate. The rock is interesting for several reasons. The clasts are either highly angular (meaning parts are a breccia) or very well rounded; the clasts are volcanic in origin; and the matrix includes recrystallized belemnites. The composition suggests that the main sediment source (if not the only one) was a set of offshore volcanic islands.