UPPER CRETACEOUS. 647 



Emmons and Merrill ^^^ sum up the work of previous writers and give their own 

 observations in latitude 30°. The section which accompanies their article has been 

 compiled in the map of North America, as is shown by the details of distribution of 

 granitic and metamorphic rocks in that latitude. If we knew the distribution, 

 the great mass of granite which is shown as the backbone of the peninsula would 

 undoubtedly prove to be broken up by areas of metamorphic rocks of greater or 

 less extent, which are presumably to be assigned to the Mesozoic or Paleozoic, 

 and by patches of the "Mesa sandstones" and volcanic rocks which overlie the 

 intrusive and metamorphic rocks that cap the peaks and ranges. 



Lindgren'?® gave the following account of Cretaceous strata at Ensenada: 



The first evidence of the existence of Cretaceous strata in Lower California was furnished 

 by a few fossils sent to the National Museum by Mr. C. R. Orcutt, of San Diego, who found 

 them at the southern shore of Todos Santos Bay. 



Dr. C. A. White has mentioned and described those fossils. * * * The exposures are 

 not very extensive; they are, in fact, limited to a patch about 3 miles long east and west and 

 1 mile north and south, on the northern side of Punta Banda. This promontory consists mainly 

 of old porphyritic rocks, against which the Cretaceous strata have been deposited; they form 

 a perpendicular sea clifl about 50 feet high and extending for about 2^ miles along the shore; in 

 most places post-Pliocene gravel and sand cover the top of the cliff, but Cretaceous exposures 

 may be found a little higher up, protruding from the later, covering beds. 



The strata consist of a series of yellow coarse sandstones, interstratified with heavy con- 

 glomerates of well-rolled pebbles up to a foot in diameter, evidently petrographically identical 

 with the massive rocks forming the peninsula and derived from them. * * * 



In these heavy sandstones, generally void of fossils, there are at intervals strata 2 to 4 

 feet thick composed entirely of the calcareous shells of Coralliochama, accompanied by a small 

 specimen of Cerithium. The fauna is decidedly monotonous, and but a few new forms were 

 found. 



There are strong reasons for believing that this isolated Cretaceous mass is but the first of 

 a series of similar strata farther south, and I only regret that I could not extend my trip in that 

 direction. On Todos Santos Island, about 12 miles from the coast, there appears to be an 

 exposure of sandstone similar to that of Punta Banda. At the harbor of Santo Tomas, 40 

 miles south of Ensenada, a steep sandstone cliff, containing many and large pebbles, is said to 

 form the coast. Similar sandstones occur at Cape Colnett, about 70 miles south of Ensenada. 

 From here it is not very far to where the Mesa sandstones begin, and it appears to me quite 

 probable that these also will eventually be found to belong to the Cretaceous period. Gabb 

 has followed the sandstones more carefully on the eastern than on the western coast and states 

 expressly, regarding the former, that they continue to skirt the coast for a long distance north 

 of the end of the second or middle division, where they occupy the whole peninsula. His 

 description of the appearance of the sandstone corresponds very well indeed with the Todos 

 Santos occurrence. It must be remembered that Gabb did not determine the age of the Mesa 

 sandstones, but only conjectured, based on a very slight clue, that they were Miocene. At the 

 same time he describes the quite extensive metamorphism which has affected the strata in cer- 

 tain regions. This fact can not well be brought into accord mth such a comparatively recent 

 age as that to which he assigns the rocks. At least nothing has been observed in Upper 

 California indicating that any extensive metamorphism has occurred so recently." 



The strata which occur at Todos Santos Bay were placed in the Wallala group of 

 White, which has since been recognized as lower Chico. 



a The character of the Miocene series recently found in the southern part of the peninsula at Boleo * * * 

 appears to be very different from the Mesa sandstones and from the Todos Santos occurrence; it also incloses volcanic 

 materials of andesitic and basaltic character. It is probable that the shells referred to abo^'e (Ostrea) came from a 

 series equivalent to this and not from the Mesa sandstone. 



