370 GEOLOGICAL SURVEY OF THE TERRITOEIES. 



nized as a liomogeneoiis single formation, I argued that, the same dis- 

 accord being remarked in our Lignitic measures, we had to explain it in 

 the same way, and should not, on that account, force an abnormal divis- 

 ion of a formation whose flora is positively analogous or synchronous 

 in its characters in the whole thickness. A discrepancy of the same 

 kind is recognized in the Cretaceous formations of Europe, even between 

 the groups of animal fossils which characterize them. The- president 

 of the Society of Natural History of Geneva, my honored friend, Eev. 

 Duby, says, in his discourse of 1861, in regard to the geological observa- 

 tions recorded during the year, 



That the society had been favored by Professor Pictet with numerous communica- 

 tions relative to paleontology, of which the most imi^ortant is a notice of the sncces- 

 eion of the cephalopod mollusks dnring the Chalk period in the region of the Swiss 

 Alps and Jura. Mr. Pictet derives, from a detailed study of the fossils contained in the 

 Cretaceous strata and their comparison with contemporaneous repositories, an argu- 

 ment in favor of the idea propounded by Mr. Barande, that two successive faunas 

 must necessarily have existed together for some time, and he concludes by showing that 

 paleontological faunas, distinguished through by marked characters, are not ordinarily 

 susceptible of any rigorous limitation. 



Messrs. Claparede and Favre took occasion to remark on this, how 

 much the conclusions of Mr. Pictet must in future complicate the task 

 of geologists who undertake to determine the age of the formations. On 

 the same subject Count Saporta, one of the highest European authori- 

 ties in vegetable paleontology, remarks,* in speaking of the presence 

 of Ammonites, BacuUtes, Inoceramus, &c., in the American strata, which, 

 by their fossil plants are characterized as Eocene, that these mollusks 

 have persisted for a longer time in the Cretaceous of America than in 

 Europe ; a fact which is easily admitted, as, in Erance, the chambered 

 cephalopods had left the Cretaceous seas of the south long before they 

 disappeared from the north. The same remark is repeated in Jukes 

 and Geikie's Manual of Geology, (p. 664.) 



In parts of the north- of France there occur curious banks of white pisolitic lime- 

 stone, resting apparently in hollows of the chalk, &c., but sometimes on the same level 

 as the lower beds of the Tertiary rocks above it. Some of the'fossils are true Creta- 

 ceous, while none, I believe, are Tertiary forms. 



We have apparently something like this in our geologica,l Upper Creta- 

 ceous formation, if, as it seems proved, we do not find any kind of Cre- 

 taceous mollusks in the Lignitic basin of Golden, when their presence is 

 still ascertained in the Lignitic of Bear Eiver and Coalville. The English 

 geologists remark on facts of this kind, {loc. cit, p. 665:) 



That the existence of local grouj)s of rocks that will not exactly fit into the general 

 series, either from their containing fossils different from those found in any other group, 

 or from their uniting parts of two sets of fossils which are elsewhere distinct, although 

 sometimes perplexing, seems neither unnatural nor different from what might be 

 expected. It merely shows us that our geological series is a series of fragments, not one 

 of absolutely continuous succession. 



In his travels with the Hassler, Professor Agassiz has observed a 

 case which may serve to explain anomalies between the records fur- 

 nished by animal and vegetable remains in regard to the age of the 

 strata, t 



The geology of the coast of Possession Bay is interesting to the highest degree. 

 All along the coasts, north of the Straits of Magellan, the Tertiary formations, same as 

 along the coasts of Eastern Patagonia, are perfectly distinct, even seen from a distance, 

 by their horizontal strata, also remarked on the coast of Fuego. In Possession Bay we 

 landed to more carefully recognize the character of the country, &c. One mile 

 inland from the cliffs I found, at 150 feet above the sea-level, a pond of salt water, which, 

 to my great surprise, had an abundance of marine shells, identical with those of the 

 sea along the coast. They were in a perfect state of preservation ; many were living, 



* In letters. 



t Letter of Professor Agassiz to Professor Peirce, in Boston Advertiser. I have to re- 

 translate this from the French Bevue scientifiqiic, No. 4G, May, 1873. 



