246 J. B. Hatcher — Cape Fairweather Beds. 



Art. XXYII. — The Cape Fairweather Beds ; a new marine 

 Tertiary Horizon in Southern Patagonia / by J. B. 

 Hatcher. 



In July, 1896, the writer discovered near Cape Fairweather, 

 in south latitude about 51° 31/, a series of marine beds with a 

 fairly abundant invertebrate fauna, overlying the fresh water 

 Santa Cruzian beds, which are well represented in this vicinity 

 and contain abundant remains of fossil mammals. It is pro- 

 posed to call these deposits the Cape Fairweather beds from 

 the name of the cape near which they were first observed. 



Going north along the shore, from the mouth of the 

 Gallegos river, the Cape Fairweather beds are first seen at a 

 distance of about two and a half miles, capping the summit 

 of a high tableland on the north side of a rather deep canon, 

 which empties into the sea from the west. From this point 

 these beds were traced six or eight miles farther north, along 

 the bluffs of the coast; and were seen to extend for some 

 distance westward into the interior, constituting the summit of 

 the higher tablelands. In most places, where present, they 

 are easily recognized by the remains of a large oyster, frag- 

 ments of which may be seen in great abundance near the sum- 

 mit of the more precipitous bluffs in this vicinity. They are 

 best represented on Rudd's farm, but are also to be seen on 

 the bluff southeast of Mr. Jose Monte's farmhouse, some six 

 miles inland, though not well displayed. 



The Cape Fairweather beds have been deposited upon the 

 eroded surface of the Santa Cruzian beds, as shown by the 

 accompanying section, which was drawn from a sketch made 

 in the field, and represents very accurately the section of the 

 two series of strata on the north side of the canon above 

 referred to from the top of the tableland, which is reached at 

 2, to the level of high tide represented by the line a — o. 

 The bluff here, as almost everywhere along this coast, is quite 

 perpendicular, and the color, composition and relations of the 

 various strata are easily seen. The irregular line c — d is the 

 line of contact between the two series of beds and shows well 

 the eroded surface of the lower series upon which the upper 

 beds were deposited. 



These new marine deposits are of no very great thickness, so 

 far as observed, only 30 to 40 feet. They consist below of a 

 fine-grained, incoherent sandstone ; and above, of a rather 

 coarse, usually loose, but in places, extremely hard conglomer- 

 ate which passes insensibly into the overlying great Pata- 

 gonian Shingle formation, from which it can only be distin- 



