What is a sag pond?
The San Andreas Fault is right out our back door! Literally! And there is great evidence of this as we walk the trails. One example is a Sag Pond. This particular Sag Pond is along our Hillside Loop Trail hike. This is a very common feature of the San Andreas Fault zone.
Sag Ponds are formed in the low spots between the ridges and/or when stream drainage is offset and blocked by horizontal movement within the fault zone. The water does not drain from the sag ponds because the rocks in the fault zone have been ground to a fine clay from the "rubbing" of the Earth's movement and are thus impermeable. Water collects and wa-la you have a pond.
Madge Malone in her blogging zone!