Dirt (Part I)

For the next few weeks, I am going to write about “dirt.” Not political dirt, not Hollywood dirt, just plain dirt—the kind we have underneath us, some of the best dirt in the world.

How did we get this dirt? Unfortunately, we are sitting on top of the intersection of two great tectonic plates: the North American Plate to the east and the Pacific Plate to the west. These masses are floating atop liquid magma and bump up against each other right where we live. Where they meet, they have developed faults due to the Pacific Plate moving northward faster than the North American Plate.

The Hayward fault, extending south along the east bay to Milpitas, is considered to be the most dangerous fault. On the other side of the bay of our valley lies the San Andreas Fault, extending from the Sea of Cortez, dividing the Baja Peninsula from mainland Mexico, and running through California to the north of us where it continues under the Pacific Ocean. It was the San Andreas Fault that gave us the great quake of 1906. In 1868, there was a major quake along the Hayward Fault. Andrew Hill, the famous local artist, lived through both and said he felt the Hayward quake was more severe.

Over the eons, these faults pushed up the mountain ranges bordering our valley: the Diablo (or Mt. Hamilton) Range to the east and the Santa Cruz Range to the west. Between the two, winter rains carried topsoil down the slopes and created our fertile valley, the “Valley of Heart’s Delight.” A huge basin of fresh water, and aquifer, developed deep underground—water that would later irrigate our crops and quench our thirst.

The Indians first arrived about 12,000 years ago, settling in the lowlands where life was relatively easy and food plentiful. Because the climate was so mild, they never built permanent shelters like the Indians in the Northwest, Alaska and the Southwest. These local Indians had three major gods: Eagle, Coyote and Humming Bird. Mt. Umunhum was named by these Indians, and while we don’t pronounce the “h” in Umunhum, we should because the flutter of the bird’s wings is the same to us as it was to them.

The Indians had a legend that the Golden Gate was created by a great earthquake, and that before the quake, the Santa Clara Valley was submerged and part of San Francisco Bay, with the bay’s outlet at Moss Landing. This makes sense to me. Here in the south valley, Coyote Creek flows northward, while directly on the opposite side of the valley, near Morgan Hill, the Pajaro River flows south and then west to meet the Pacific Ocean near Watsonville. There, at Moss Landing, the river enters the Pacific at the undersea Monterey Canyon. This ancient canyon is as deep as the Sierras are high, nearly 9000 feet deep where it intersects a line running between the cities of Santa Cruz and Monterey. Those two streams, the Coyote and the Pajaro, carried the silt that made our valley’s rich soil.

2 Comments

  1. While I’ve lived in the area most of my life, I’ve never paid much attention to how it got here..of course, part of that would be acknowledging how much earthquakes rule this area (and who really wants to go there?).  Didn’t realize, for instance, we had rivers/creeks flowing in different directions due to this..thanks, it’s fascinating.

  2. I was always told that the reason that our Bing cherries from that area Willow Glen thru Saratoga and up to Sunnyvale were so large, sweet and wonderful was that cherry trees were very deep rooted and that area had 90 feet of soil! Our rivers and creeks deposited it and the Pioneers planted and grew the trees.

    One other thing, Leonard once told me that he tinks those little trails that you see on the steep hillsides were NOT paths that the animals made, but rather the water level marks from those old days when the out flow from our valley was in Watsonville!

    But, who can believe an old historian?

    Jerry