laces, 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