TO JUNCTION OF GRAND AND GREEN 1U VERS. GO 



of tools, and a familiarity with the business of mining. The roof is carefully braced 

 where weak, and old galleries are closed by well-laid walls of masonry. From the 

 Btyle in which the excavation is done, and from the perfect preservation of the wood- 

 work, 1 attribute this and other similar mines in this region to the earlier Spanish 

 explorers. The rock which contains the ore is very coarse, frequently a conglomerate, 

 witli hands of light-gray clay. The copper is distributed with considerable uniformity 

 through a layer four or live feet in thickness. It occurs in the form oi' sulphide of 

 copper and iron, (erubescite,) and green carbonate, replacing trunks of trees and frag- 

 ments of wood, and in concretions and botryoidal masses scattered among the pebbles 

 of quartz, or as minute points of carbonate specking the shales. It has evidently been 

 deposited from solution, investing and replacing the wood precisely as the sulphide of 

 iron is prone to do. 



"The most interesting incident of our visit to this copper-mine was the discovery 

 in the shale roof-stone of thousands of Impressions of plants, of which abundant speci- 

 mens were procured. They are mostly cyeadaceous — Otazamites and Pterozamites — 

 with a few conifers (BraehypKyllum and VoMziaf). The species are probably new, and 

 will not afford the means of determining with precision the age of the stratum contain- 

 ing them, but the discovery is of great geological interest, as showing the wide distri- 

 bution of the cyeadaceous flora of the Triassic and Jurassic epochs, and gives addi- 

 tional confirmation of the generalization of Brongniart, who characterized this epoch in 

 the botanical history of the world as the reign of Gymnosperms."* 



On the 19th of July w r e left Abiquiu for the ascent of the A.biquiu Peak. My 

 notes of the trip are as follows: 



"Left camp at 7 a. m. The train, moving on to the Arroyo Seco, passed up the 

 Ohama to a point just above Ahiquiu, and then turned to the left and ascended, by a 

 long and difficult road, the high mesa which overlooks the valley on the south side. 

 This mesa is here full a thousand feet above the Chama, and is connected with that of 

 which the broken edge forms a bold headland below the town, known as Abiquiu 

 Cliff. The upper part of this mesa is composed of trap, below which are exposed sev- 

 eral hundred feet of the variegated marls (Trias), and the white tufaceous Tertiary beds, 

 all quite soft, and, in man)- places on both sides of the Chama, very fantastically eroded. 

 The mesa over which we passed extended, with a nearly level surface, several miles 

 toward the peak. It is covered with groves of pinon, separated by prairies uniformly 

 coated with grama grass, now very short and dry. Arriving at the western border of 

 this mesa, we looked directly down into the narrow but fertile valley in which is nestled 

 the little Mexican village of Los Canones. Descending by a steep and tortuous path, 

 we left our mules at the bottom and climbed a detached mesitta which stands at the 

 junction of the two branches of the valley, and on which is situated an ancient and 

 ruined pueblo, once a stone-built town of considerable size. Even its name is now lost, 

 and of the inhabitants whose busy hands constructed its walls, and whose feet in suc- 



I )<s ( riplions of these plants will be found in another Chapter, where it is shown that the most conspicuous BpecieB 



(Otozamites Macombii) is the same with one found in the Triassic strata of Lob Broncos, Sonora, when- it oconrs in com- 

 pany witli Peoopterls Stutgardtensis, TasitiopterU magnifolia, and other well-known Triassic plants of Virginia, North Caro- 

 lina, and Europe. We have, therefore, in these plants evidence of the Triassic age of nil the variegated gypsiferous 



imks of northern New Mexico; for the Low.t Cretaceous sandstones immediately overlie the plant-bed of the Cobrc. 



