Sidewalk contractor stamp: T. F. Costella, Contractor.
Branciforte neighborhood, Santa Cruz, CA

I’m 80% confident that this is the same company that did the concrete for the <a href=”http://en.wikipedia.org/wiki/Giant_Dipper#cite_note-Santa_Cruz_Beach_Boardwalk:_The_Early_Years–_Never_a_Dull_Moment-2″>Big Dipper in 1924</a>. Wikipedia says it was a TF Costello, but the source document returns a 404.