234 Scie?itific and General Memoranda. 



(well known, however, to most of the officers attached to the 

 Yellow Stone expedition,) I shall feel more than compensated for 

 any time 1 shall devote to the subject. 



The enclosed specimen was broken off from one of the many 

 large stumps and limbs of trees, found near Yellow Stone River, 

 and brought away by some one of the officers attached to the 

 Yellow Stone expedition in 1815. 



The most remarkable facts, perhaps, with regard to these pe- 

 trifactions, of what was once a forest of thick timber, are their 

 location and abundance. For a distance of twenty or thirty 

 miles, over an open high prairie, upon the west bank of the Mis- 

 souri river, and a few miles below its junction with the Yellow 

 Stone, near latitude 48°, these remains are more abundant. 



The topography of this section of the country is hilly, and 

 much broken into deep ravines and hollows. On the sides and 

 summits of the hills, at an elevation of several hundred feet (esti- 

 mated three hundred) above the present level of the river, and 

 an estimated height (for we have no instruments) of some thou- 

 sand feet above the ocean, the earth's face is literally covered 

 with stumps, roots, and limbs of petrified trees ; presenting the 

 appearance of a " Petrified Forest," broken and thrown down 

 by some powerful convulsion of nature, and scattered in all di- 

 rections in innumerable fragments. 



Some of the trees appear to have broken off, in falling, close to 

 their root ; while others stand at an elevation of some feet above 

 the surface. Many of the stumps are of a large size ; I measur- 

 ed one of them, in company with Surgeon Gale of the United 

 States army, and found it to be upwards of fifteen feet in cir- 

 cumference. 



The following is a description of the Mexican Pyramids, allud- 

 ed to at page 177 of our last number. — Ed. 



Pyramids of Tcotihuacan in Mexico. — At a recent meeting of 

 the London Geographical Society, a communication was read 

 from licut. Glennie, descriptive of these interesting memorials. 

 The village of Tcotihuacan is in lat. 10 deg. 43 min., N. and in 

 long. 98 deg. rA min. W. : the variation of the needle being 9 deg. 

 49 min. E. The village is elevated 7,492 feet above the level 

 of the sea. The pyramids are distant about a mile and a half 

 from it : the largest is 727 feet square at its base, and 221 feet 



