The rocks of Santa Cruz, as in many other places, were laid in regular order, like the leaves of a book on its side. But by various forces they have been crumbled, some torn out, and in many places piled together. These layers, beginning at the bottom, are as follows; (1) igneous granite, unstratified; (2) limestone laid down from life in the ocean, metamorphosed by heat and all fossils thereby destroyed; (3) limestone highly crystallized, composed of fossil shells and very hard; (4) sandstone, made under the sea from previous rock powdered, having huge concretionary masses with a shell or a pebble as a nucleus around which the concretion has taken place; (5) shale from the sea also; (6) conglomerate, or drift, deposited by ice in the famous glacial cold snap; (7) alluvium soil deposited in fresh water and composed partly of organic matter. In our second illustration some of these layers, or strata, may be distinguished.
[Illustration: The Work and the Worker, Santa Cruz, Cal.]
When the awful blows of the sea smite the rock, if it finds a place less hard than others, it wears into it a slight depression, after half a hundred thousand strokes, more or less, and ever after, as the years go by, it drives its wedges home in that place. A shallow cave results. Then the waters converge on the sides of the cave and meet with awful force in the middle. Thus a tunnel is excavated, like a drift in a mine, each wave making the tremendous charge and the reflowing surges bringing away all the detritus. This tunnel may be driven or excavated two hundred feet inland, under the shore. At each inrush of the wave the air is terribly condensed before it. It seeks outlet. And so it happens that the air is driven up through some crack in the rock and the superincumbent earth, one or two hundred feet from the shore, and a great hole appears in the ground from twenty to seventy feet deep. Then the water spouts fiercely up and returning carries back the earth and broken rock into the sea.
No. 3 of the illustrations here given represents such a great excavation one hundred feet back from the shore. It is one hundred and fifty feet long by ninety wide and over fifty feet deep. All the material had been carried out to sea by the refluent wave. On the natural bridge seen in front the great crowd in Broadway, New York, might pass or a troop of cavalry could be maneuvered. Through the arch a ship with masts thirty feet high might enter at high tide. Through the abutment of the arch where the afternoon sun pours its brightness the waves have cut other arches not visible in the picture. When the arches become too many or too wide the natural bridge will fall and be carried out to sea like many another.
[Illustration: A Natural Bridge, Santa Cruz, Cal.]
But what does the sea do with the harder parts of the cliff? Its waves wear away the rock on each side and leave one or more long fingers reaching out into the sea. The wear and tear on such a projection is immense. A strong swimmer may play with the breakers away from the cliff. At exactly the right moment he may dive headlong through the pearly green Niagara that has not yet fallen quite to his head and may sport in the comparatively quiet water beyond, while the wild ruin falls with a sound of thunder on the beach. But let him once be caught and dashed against the rocks and there is no more life or wholeness of bones within him.