Mineralogy and Geology. 419 



the sides of Pichincha, and the present cone is far from being considera- 

 ble enough to have furnished such a vast quantity of projectiles. Those 

 which were thrown at angles less than 45° would strike against the 

 inner walls of the crater, and roll back again into it ; those only which 

 were thrown at greater angles, and with force enough to rise 16,000 

 feet above the plain of Quito, could reach their present positions ; and 

 although this is not physically impossible, yet it is contradicted by the 

 appearances of the later eruptions, which have clearly been of a very 

 tranquil description. 



The authors consider as equally fabulous, a tradition that the erup- 

 tion of 1660 was accompanied by showers of incandescent rocks, which 

 are said to have fallen on all sides, but of which not a vestige is now to 

 be seen. J. C. M. 



5. Count Keyserling^s Geology of the Northeastern Extremity of 

 Russia in Europe; by Sir R. I. Murchison, (Proc. Brit. Assoc, 1847, 

 Athen., No. 1028.) — SirR. I. Murchison exhibited the new work, en- 

 titled, " Wissenschaftliche Beobachtungen auf einen Reise in das Pets- 

 chora-Jand"* and explained its value in completing the acquaintance of 

 geologists with the great northeastern angle of Russia in Europe, which 

 is watered by the river Petschora. The geographical and astronomical 

 observations in this expedition (to a region previously known only im- 

 perfectly to the Russians through the traders in fur) are by M. P. von 

 Krusenstern, of the Imperial Navy. The geological outline of the 

 present work (executed in 1843) was communicated to Sir R. 1. Mur- 

 chison previous to the publication of the volumes on the "Geology of 

 Russia and the Ural Mountains," and constitutes one of the chapters of 

 that work ; but the object of this communication was to call attention to 

 the additions which had appeared: first, in regard to the physical and 

 geological delineation of this wild country in two maps; and, secondly, 

 to the numerous plates (twenty-three in number) of the organic re- 

 gains of the Silurian, Devonian, Carboniferous, Permian, and Jurassic 

 systems, occurring in a hitherto unexplored region which extends over 

 near 11 degrees of latitude ; viz. from 60° to 71° N. lat., and 25° long., 

 including the northernmost range of the Ural Mountains. Sir R. I. 

 Murchison stated that although the eastern flank of that chain had been 

 touched upon at one or two points by the authors, and notably in N. 

 lat. 65°, enough had only just been done by them in this respect to 

 connect, in an approximate manner, the structure of the northern end 

 °f the chain with that previously described : all this rocky territory, 

 extending 3° and 4° of latitude beyond the limits of arboreal vege- 

 tation, is now under the survev of a distinct expedition, commanded by 

 Col. Hoffman, and sent out under the auspices of the Geographical So- 

 ciety of St. Petersburg. The chief geological interest attached to the 

 *ork of Count Keyserling, (in addition to the points alluded to,) is the 

 determination of an axis of palaeozoic rocks constituting the Timan 

 R »dge, which, branching off from near the Ural Mountains in !at. N. 

 88°, trends in a N.N.VV. direction to the left bank of the Petschora to 

 the bay of Techeskaya, and is prolonged into the promontory of Kanin- 



* Thig work consists of a 4to volume of text, published in German at St Peters- 

 burg in 1846, with 23 elegant 4to plates of fossils, and two mapi.-— J. D. D. 



