It will be also unavoidable to forego the examination of the sedimentary rocks, rich in fossils, between Honda, Bogotà and Ibagues, the Mastodon fields (Campos del Gigante), and the Salto de Tegumidama on the plateau of Bogotà, the wax palm (Ceroxylon Andicola), and the Azufrales of the Passo de Quindiu, the volcanoes of Tolima, measured by myself and ascended by Boussingault, and of Paramo de Ruiz (4° 15′ N.), as also the two volcanoes of Popayan, the Puracé and the much more interesting but now extinct Sotará. As a middle course, I may suggest a disembarkation, not exactly at Guayaquil, but on the gold and platinum coast of the Choco, near San Buenaventura, so as to proceed thence to Popayan, and afterwards return to the volcanoes of the province of Pasto, which are highly important, and so on to Quitó, by way of Guachucal, Tulcan, and Villa de Ibarra, rejoining the frigate only at Guayaquil.
I believe, however, it would be more advisable to select Quitó as the starting-point, whence to examine the important elevated volcanic region De los Pastos (between 2° 20′ and 0° 56′ N.), containing the volcano of the town of Pasto, the volcanoes of Tuguerres, Chiles and Cumbal, and the Azufral de Pasto, and not to land at any port of the Choco coast, not even from the Bahia de Cupica, which for half a century I have recommended in vain on account of its vicinity to the Rio Naipi, one of the tributaries of the Atrato. In drawing up a list of names of the volcanoes of the renowned lofty plateau of Quitó, I may include, Imbaburu, Cotocachi, Rucu, Pichincha, Antisana, the much-disputed question of the stony walls like streams of lava, on the east slope of Tana Volcan, and Reventazon de Ansango; Cotopaxi, with its strange inexplicable quarries of pumice, of Guapecho and Zumbalica, in the neighbourhood of Llactacunga and San Felipe, the pumice containing oligoclase, not glassy felspar, deposited in strata, like any rock in situ for a considerable distance on all sides of Cotopaxi; Tunguragua (mica slate), studded with garnets, and beds of granite, which dip under the former, and have themselves been pierced by the trachytes of Tungurahua at Rio Puela and the Hacienda de Ganace; the hills of Moya, near the village of Pelilco, cast up in the celebrated earthquake of 7th February, 1797, and still in a state of activity; the Chimborazo, which M. Jules Rémy, accompanied by an Englishman named Princkley, was in the belief they had ascended, on the 3rd of November, 1856, to the very summit, "mais sans s'en douter." Poggendorff, (Vol. X. p. 480), has clearly demonstrated that the boiling point given by Rémy for the summit, would not give 6544 mètres (little different from my own trigonometrical admeasurement of 6530 mètres), but fully 7328 mètres. As I distrust my own half-barometical measurements, I have vainly implored travellers, these fifty years past, to have a new series of trigonometrical observations made of the summit of Chimborazo. The merit, then, of settling this moot point, it also remains for the members of the Novara Expedition to obtain.
It would be important to examine the Sangay (16,068 feet)—which, like Stromboli, is in constant activity, yet without any traces of lava-streams—on account of the grains of quartz discovered by Wisse in the trachytic boulders ejected by the volcano, which is of such rare occurrence in the trachytes out of Hungary; and also on account of the close vicinity of beds of granite and gneiss, which are broken through by the Sangay trachyte, forming an island, as it were, of not hardly two miles in breadth. Still more deserving of attention is the extinct volcano El Altar de los Collanes (Capac Urcù) a sketch of which I presented in the atlas published in my "Kleine Schriften" (Plate V. p. 461), formerly higher than Chimborazo, and still (?) 16,380 feet. Not a single specimen of its trachyte has ever been deposited in a European museum. The Altar itself is readily accessible from Riobamba Nuevo. In its vicinity may also be seen mica slate and gneiss, cropping out at the Paramo del Hatillo near Guamote, and Teocaxas, which are so seldom fallen in with in the highlands of Quitó. Tradition relates that gold-mines were worked here during the days of the Incas, in the neighbourhood of volcanic trachytes. From the Altar the geologist might proceed, by way of San Luis, (Query, whether the primitive clay-slate found here be of the Silurian formation?) and Guamote, to Paramo del Assuay (2428 toises), and Cuenca, as far as Atausca (2° 13′ S.), where an immense mass of sulphur, lying in a quartz seam is worked, forming a bed in the mica slate. Of what rock does the easily accessible Cayambe Urcù (18,170 feet) consist, crossing the Equator, S.E. of Otavalo? En route from Quitó to Cayambe, the rich deposits of obsidian near Quinche should also be inspected, which furnished the large mirrors to the Incas, and farther to the north of which are the volcanoes of Los Pastos, which form a separate system by themselves.
For examining the rocks and exploring the volcanoes of Southern Peru and Bolivia—respecting which see the last edition of Pentland's Maps, not those published between 1830 and 1848, in which the height of Sorata was indicated at 3949 toises (25,257 feet), and Illimani at 3753 toises (24,004), and accordingly both as much more lofty than Chimborazo, which is 3350 toises (21,426 feet)—the best starting-point would be the port of Arica, which may be reached, sailing the whole distance against the cold current, from Guayaquil, after a short stay at Callao de Lima. Of the volcanoes of Peru and Bolivia only three are now active.
(a.) The volcano of Arequipa, three miles N.E. of the town of the same name, which, according to Pentland and Rivero, is situated about 7366 feet above the level of the sea. The measurements of M. Dolley, of the French navy, which were published under my superintendence, give the summit of the volcano as 10,348 feet above the town of Arequipa, so that its total elevation above the sea would be 17,714 feet. In the table of heights for Mrs. Somerville's "Physical Geography," Mr. Pentland speaks of the summit as being 20,320 English feet in height, or 19,065 Paris feet, closely approximating to the old trigonometrical measurement (19,080 feet) given by Thaddeus Haenke, a Bohemian, who accompanied the expedition of Malaspina, in 1769. What a deplorable state for the science of hypsometry to be in! which the Novara ought to put an end to. Samuel Anzon, a North American, in 1811, and Dr. Weddell, in 1847, have ascended the volcano of Arequipa.
(b.) Sahama (18° 7' S.), according to Pentland's new map of 1848, is 871 feet higher than Chimborazo (which he gives as 20,970 feet), and is still active. The true heights of Illimani and Sorata, ascertained since 1848, are, instead of 3949 and 3753 respectively, only 3329 toises (21,266 English feet), and 3307 toises (21,145 English feet).
(c.) Volcano Gualatieri, in the Bolivian province of Carangas (18° 25′ S.), height 20,604 feet.
The southern group of South American volcanoes, that, of Chili, presents the largest number of active fire-mountains—only second, indeed, to that of Central America, there being from eleven to thirteen. In order to increase the geological exploration of this region which has been so well prepared by the memorable expedition under Captain Fitzroy, in the ships Adventure and Beagle, the excellent generalizing theories of Mr. Darwin, and the naval astronomical expedition of Mr. Gilliss, for 1849-51, the Novara will probably land at Valparaiso. A great desideratum between Coquimbo and Valparaiso is an exact measurement of—
A. The volcano of Aconcagua (32° 39′ S.). Its height has been stated, in 1835, by Captain Fitzroy, as 21,767 feet, Pentland's correction assigning 22,431 feet; while Captain Kellet, of the frigate Herald, gives it as 21,584 feet. Miers and Darwin are both of opinion that the Aconcagua is still in activity, which is denied by Pentland and Gilliss. The most recent measurement of Aconcagua—that by Pissis in 1854 (see Gilliss, Vol. I. p. 63)—makes the height 20,924 feet. M. Pissis has published, in the "Anales de la Universidad de Chili," for 1852, the geodetical elements of his survey, which is based upon eight triangles. Aconcagua being probably the highest mountain in the New World, a new measurement is eminently desirable. Neither Dhawalagiri, with his 4930 toises, nor Kintsinjunga, measured by Colonel Waugh, with his 4406 toises, are any longer considered the highest mountains in the Himalaya range, but the Deodunga (Mount Everest), which is 29,003 English feet, equal to 27,212 Paris feet, or 4535 toises.
B. The volcano Maipu (34° 17′ S., height 16,572 feet), ascended by Meyen. The trachytic rock on the summit has broken through the Jurassic strata, in which Leopold von Buch has ascertained, from heights of 9000 feet, the existence of Exogyra couloni, Trigonia costata, and Ammonites biplex. This volcano has no streams of lava, but only eruptions of volcanic slags. It would be most desirable that Dr. Hochstetter should examine this remarkable protrusion of dislocated strata.