. Bulletins of American paleontology. Baja California Stratigraphy: Carreno and Smith 69 part of tlie San Felipe quadrangle were presented by Boehni ( l&#39;^)S2). The thickness of the marine section is estimated as 100 m. San Felipe Diatoiiiite Meiuher. Late Mioeene-Early Plioeene.—Boehm&#39;s lower member was described from exposures along the eastern side of the southern Sierra San Felipe. The unit is more than 30 m thick and contains Late Miocene, middle bathyal diatoms, silicoflagellates, radiolarians. and deep-water tbramin- ifers that suggest marine deposition in the embayment began at 6.0—5.5  - Stock Image