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If you have been wondering about the origin of the foam you can often find on the beach during the summer, it has noting to do with soap suds.It is caused by the decaying remains of microscopic organisms in the sea.

Every spring the ocean has sudden bursts of life. Phytoplankton bloom starts at the end of March. After a couple of weeks tiny algae like diatoms occur in such numbers that the water becomes yellow-brown.

So, what is that black stuff on the beach in Fort Funston? Is it oil left over from the Cosco Busan spill? No, in fact it is the chalky substance-veins of volcanic ash thrown from Mount Lassen thousands of years ago. After all of our heavy storms this winter, most of the top layer of silica sand had been blown or washed away to leave dark colored streaks on the beaches. This black sand is a kind of iron ore called magnetite. The magnetite is a part of the cliff walls, and as the sandstone erodes, it leaves the heavier iron-based magnetite on the beach.

Black sand can be seen as a layer on top of silica sand in regions with high wave energy. This weight enables it to remain when high-energy waves wash the lighter sand grains out into the surf zone.

Take a magnet with you to the beach and run it through the sand, magnetite will stick to the ends. The dark minerals in beach sand at right, from Fort Funston are primarily magnetite and amphiboles, which are non-magnetic black minerals. Both of these mineral types tend to fracture into very small grains that collect on the surface of the sand, by virtue of being smaller and, therefore, lighter.

Have you ever run into horseback riders at Fort Funston?

Well if not, you probably will someday soon.  Fort Funston is a popular destination for equestrians of all skill levels.

Don’t know how your dog will react to a horse? I suggest that you keep your eyes open and if a horse approaches, put your dog on leash, until you know their behavior. Most dogs will have a natural curiosity around horses and may run up to sniff or bark, which may startle the horse and cause the rider to fall, or at the very least, the rider may become angry with you and make it an unpleasant encounter.

Until you know how your dog will react to a horse,it is important to make that first encounter a cautious one. If you find that you dog seems to be overly interested in the new beast on the beach, then I recommend that you do some conditioning. I have had very good luck with dogs that are reactive to horses on the trail, if I take them on a private walk to a stable, on leash of course, and coax them near the horses with cookies and lots of baby talk (yes this is a technical dog training term). After a few times, the dogs will feel more secure and will relax around horses. And if you should see horses on the beach, you should call your dog over to you, for a treat. If you have conditioned the dog well enough, they should not react to the horses passing, but rather come over to you and sit facing you, when you call out “cookie” and then request that they “sit” quietly while the horses pass.