[3][7] In general, the sandstone layers become more common towards the top of the stratigraphic column, and the largest conglomerate bed is in the highest part of the Espada, exposed north of the Santa Ynez River near its junction with Mono Canyon.

[3] The Espada Formation represents a long period of geologic history – tens of millions of years – in which sediments were deposited in warm, quiet water in a basin that was gradually subsiding.

The water was usually shallow, as indicated by the frequent sandstone beds (coarse sediment such as sand is deposited nearer shore unless carried far offshore by submarine landslides and other subsea mass movements).

[6][8] The Espada resembles some strata of the underlying Franciscan Formation, even though the two units may have been deposited at great distances from each other, and brought together by tectonic forces along the boundaries of the Pacific and North American Plates.

[9] As the block shifted northward, the formation was also subject to folding, resulting in creation of structures such as the Mono syncline, which includes Camuesa Peak north of Gibraltar Reservoir, and the parallel Agua Caliente anticline.