Following the map on my i-phone and not too far up the trail, we made it to the edge of a small sharp slope. With the blue dot dead on our position, I am convinced that the box is located on the back of the tree which is almost within touch - the tree base way down the slope and growing up way past our level.
Henry was ready to go off trail to get the eucalyptus tree harboring the geocaching box and sign-in sheet. Unfortunately it is located in a sensitive regrowth zone.
The hint sheet said there was a trail leading around the zone to get to the spot. It certainly looked like people had scrambled down the hill. However, it was posted as a closed regrowth area. Henry and I couldn't do it. It takes too many years for the regrowth to establish itself in our semi-arid area.
We'll try again tomorrow. There is another geocaching within walking distance if we leave early - before it warms up. We left it too late this morning. By the 11 a.m. and the end of our two mile trek it was way too hot for hiking hills with limited shade. Southern California summer approaches! I forget that we go from "chilly fireplace days" to "just too hot to walk" in a day.