CRETACEOUS FOSSILS-ANTON CHICO-CUESTA. 
27 
and is an attractive feature in that monotonous landscape. It is found near Laguna Colorado, 
Camp 50. 
The lake and the bluff margin of the Llano are seen in the hack-ground of the sketch. 
Lieutenant Simpson gives such an interesting description of the table-mounds, and the country 
about them, that I quote it from his report: “ Following up Tucumcari creek, a fine view, 
made up of sugar-loaf hills and tableau mounds, and opening vistas, presents itself to your 
front. The regular stratification of these hills, their party white and red color in horizontal 
zones, and the whole surface, besprinkled as they are with stinted cedar of a dark-green color, 
will not fail to be noticed by the traveller as giving them a very beautiful and unique 
character. The formation of these hills, which are from one hundred to three and four 
hundred feet high, is at the base a red argillaceous rock, easily frangible ; next, proceeding 
upwards, a zone of sandstone rock, very friable, and of a greenish white color ; last, and upper¬ 
most, a sandstone rock, of a brownish hue, and rather coarse character. Large fragments of 
these last mentioned rocks lie scattered on the slope of the hills, and many among them, I 
noticed, presented evidences of having been subjected to the action of fire. Indeed I think 
these evidences of igneous action increase as we proceed towards the Rocky mountains, or 
primary rocks. On all these hills, and in the silt of the streams at their base, are found fossil 
shells of a species which point to the cretaceous period. This species of fossil was also found 
on the Independence route, some two hundred miles from Santa Fe, by Mr. A. Randall, of 
Minnesota, who classes it among the Inoceramus , a type of the Cretaceous formation.” 1 One of 
the flat-topped hills is crossed by the trail between Camps 52 and 53. It forms the divide 
between the bed of Hurrah creek and the Gnllinas river, an affluent of the Pecos. The upper 
strata are said by Mr. Marcou to be nodular, like those of the Llano. 
This portion of the route is in the immediate vicinity of the trail of Dr. Wislizenus in 1846 
and 1847, and his observations on the geology of that vicinity are interesting. He crossed the 
Gallinas river about twenty miles north of the line of the survey, and describes the bluffs at 
that point as consisting “of a dark bluish schistose limestone, with fossils belonging to the Cre¬ 
taceous formation.” 2 He has so marked this part of his trail on his map, and in the descrip¬ 
tion (p. 136) says the limestone on Gallinas creek was dark blue, and contained casts of Inoce¬ 
ramus. Beyond that point, towards the mountains, sandstone of different colors, red, grey, 
and white, was seen. 
Anton Cldco .—From the river Gallinas the route was upon the gypsum formation to Anton 
Chico, which is on the same deposites, and is in the valley of the headwaters of the Pecos, sur¬ 
rounded on all sides by the mesa-summits of the horizontal strata of the Llano and its northern 
extension. Mr. Marcou remarks that, at this point it appears to extend more to the north than 
south. He also observes of Anton Chico, that it is situated “ in a basin of red marl, of Triassic 
age, with sandy alluvium and diluvium.” (Notes, September 28.) 
Canon Blanco and Cuesta .—A few miles beyond Anton Chico the bluffs of the Llano approach 
so closely that the valley becomes very narrow, and the exposure of the red clay becomes very 
slight. Cuesta is situated at the base of one of these bluffs, on the north side of the Pecos. 
Mr. Marcou states that the bluffs are 800 feet high at this point, and that they exhibit a beau¬ 
tiful section. The strata which he calls “ Trias” form the base, and above them there is a sandy 
and marly dolomite ; white sandstone, with intercalations of greyish-white marly beds suc¬ 
ceeds, and sometimes beds of yellow calcareous sandstone, but less than at Pyramid mountain. 
No beds of gryphcea were found at the summit of the cliff. 
1 Simpson’s report of the route from Fort Smith to Santa Fd. I place great confidence in this determination by the 
late Dr. Randall. This gentleman had in his possession many valuable notes, and a collection of specimens made by him 
during his journey over the country to California. At the time of his assassination he was the President of the California 
Academy of Natural Sciences, and had done much in aid of science on the western coast. His death will long be deplored 
by all who are interested in the development of the natural history of the Pacific slope. 
2 Wislizenus’s Report, p. 17. 
