they were forced out through lateral fissures of the volcano, as the word reventazon would indicate. Soon returning from Suniguaicu and the Quebrada del Mestizo, we examined the long and broad ridge which, striking from N.W. to S.E., unites Cotopaxi with the Nevado de Quelendaña. Here the blocks arranged in rows are wanting, and the whole appears to be a dam-like upheaval, upon the ridge of which are situated the small conical mountain el Morro and, nearer to the horseshoe shaped Quelendaña, several marshes and two small lakes (Lagunas de Yauricocha and de Verdecocha). The rock of el Morro and of the entire linear volcanic upheaval was greenish-gray porphyritic slate, separated into layers of eight inches thick, which dipped very regularly towards the east at 60°. Nowhere was there any trace of true lavastreams30.

30 It is particularly remarkable that the vast volcano of Cotopaxi, which manifests an enormous activity, although, indeed, usually only after long periods, and acts destructively upon the neighbourhood, especially by the inundations which it produces, exhibits no visible vapours between its periodical eruptions, when seen either in the plateau of Lactacunga, or from the Paramo de Pansache. From several comparisons with other colossal volcanoes, such a phenomenon is certainly not to be explained from its height of 19,180 feet, and the great tenuity of the strata of air and vapour corresponding with this elevation. No other Nevado of the equatorial Cordilleras shows itself so often free from clouds and in such great beauty as the truncated cone of Cotopaxi, that is to say the portion which rises above the limit of perpetual snow. The uninterrupted regularity of this ash-cone is much greater than that of the ash-cone of the Peak of Teneriffe, on which a narrow projecting rib of obsidian runs down like a wall. Only the upper part of the Tungurahua is said formerly to have been distinguished in an almost equal degree by the regularity of its form, but the terrible earthquake of the 4th February, 1797, called the Catastrophe of Riobamba, has deformed the mountain cone of Tungurahua by fissures and the falling in of parts and the descent of loosened wooded fragments, as also by the accumulation of débris. At Cotopaxi, as even Bouguer observed, the snow is mixed in particular spots with crumbs of pumice-stone, when it forms a nearly solid mass. A slight inequality in the mantle of snow is visible towards the north-west, where two fissurelike valleys run down. Black rocky ridges ascending to the summit are seen nowhere from afar, although in the eruptions of the 24th June and 9th December, 1742, a lateral opening showed itself halfway up the snow-covered ash-cone. "There opened," says Bouguer (Figure de la Terre, p. lxviii; see also La Condamine, Journal du Voyage à l'Equateur, p. 159), a new mouth towards the middle of the part

66

In the island of Lipari, which abounds in pumicestone, a lava-stream of pumice-stone and obsidian runs constantly covered with snow, whilst the flame always issued at the top of the truncated cone." Quite at the top, close to the summit, some horizontal, black streaks, parallel to each other, but interrupted, are detected. When examined with the telescope under various illumninations they appeared to me to be rocky ridges. The whole of this upper part is steeper, and almost close to the truncation of the cone forms a wall-like ring of unequal height, which, however, is not visible at a great distance with the naked eye. My description of this nearly perpendicular uppermost circumvallation, has already attracted the particular attention of two distinguished geologists,—Darwin (Volcanic Islands, 1844, p. 83), and Dana (Geology of the U.S. Explor. Exped., 1849, p. 356). The volcanoes of the Galapagos Islands, Diana's Peak in St. Helena, Teneriffe, and Cotopaxi, present analogous formations. The highest point which I determined by angles of altitude in the trigonometrical measurement of Cotopaxi, was situated in a black convexity. It is, perhaps, the inner wall of the higher and more distant margin of the crater; or is the freedom from snow of the protruding rock caused at once by steepness and the heat of the crater? In the autumn of the year 1800, the whole upper part of the ashcone was seen to be luminous, although no eruption, or even emission of visible vapours followed. On the other hand, in the violent eruption of Cotopaxi on the 4th January, 1803, when during my residence on the Pacific coast the thundering noise of the volcano shook the windows in the harbour of Guayaquil (at a distance of 148 geog. miles), the ash-cone had entirely lost its snow, and presented a most threatening appearance. Was such a heating ever observed before? Even very recently, as we learn from that admirable, and courageous female traveller, Ida Pfeiffer (Meine zweite Weltreise, Bd. iii, 8. 170), the Cotopaxi had, in the beginning of April, 1854, a violent eruption of thick columns of smoke, "through which the fire wound itself like flashing flames." May this luminous phenomenon have been a consequence of the volcanic lightning excited by vaporization? The eruptions have been frequent since 1851.

The great regularity of the snow-covered, truncated cone itself, renders it the more remarkable that to the south-west of the summit there is a small, grotesquely-notched, rocky mass with three or four points at the lower limit of the region of perpetual snow, where the conical form commences. The snow remains upon it only in small patches, probably on account of its steepness. A glance at my representation (Atlas Pittoresque du Voyage, pl. 10), shows its relation to the ash-cone most distinctly. I approached nearest to this blackishgray, probably basaltic rocky mass, in the Quebrada and Reventazon de Minas. Although this widely visible hill, of very strange appearance, has been generally known for centuries in the whole province as the Cabeza del Inga, two very different hypotheses, nevertheless, prevail with regard to its origin amongst the coloured aborigines (Indios), according to the cne, it is merely asserted, that the rock

down to the north of Caneto, from the well-preserved, extinct crater of the Monte di Campo Bianco towards the sea, in which the fibres of the former substance run, singularly enough, parallel to the direction of the stream 31. The is the fallen summit of the volcano, which formerly ended in a point, without any statement of the date at which the occurrence took place; according to the second hypothesis, this is placed in the year (1533) in which the Inca Atahuallpa was strangled in Caxamarca, and thus connected with the terrible fiery eruption of Cotopaxi, described by Herrera, which took place in the same year, and also with the obscure prophecy of Atahuallpa's father, Huayna Capac, regarding the approaching fall of the Peruvian Empire. Is that which is common to both hypotheses, namely, the opinion that this fragment of rock formerly constituted the apex of the cone, the traditional echo, or obscure remembrance of an actual occurrence? The aborigines, it may be said, in their uncultivated state, would probably notice facts and preserve them in remembrance, but would be unable to rise to geognostic combinations. I doubt the correctness of this objection. The idea that a truncated cone, "in losing its apex," may have thrown it off unbroken, as large blocks were thrown out during subsequent eruptions, may present itself even to very uncultivated minds. The terraced pyramid of Cholula, a work of the Tolteks, is truncated. The natives could not suppose that the pyramid was not originally completed. They therefore invented the fable that an aerolite, falling from heaven, destroyed the apex; nay, portions of the aerolite were shown to the Spanish conquerors. Moreover, how can we place the first eruption of the volcano of Cotopaxi at a period when the ash-cone (the result of a series of eruptions) was already in existence? It seems probable to me, that that the Cabeza del Inga, was produced at the spot which it now occupies; that it was upheaved there, like the Yana-Urcu at the foot of Chimborazo, and like the Morro on Cotopaxi itself, to the south of Suniguaica, and to the north-west of the small lake Yurak-cocha (in the Qquechhua language, the White Lake).

With regard to the name of the Cotopaxi, I have stated in the first volume of my Kleinere Schriften, (s. 463,) that only the first part of it could be explained from the Qquechhua language, being the word ccotto, heap or mass, but that pacsi was unknown. La Condamine (p. 53) explains the whole name of the mountain, saying "in the language of the Incas, the name signifies shining mass." Buschmann, however, remarks that, in this case, pacsi is replaced by the word pacsa, which is certainly quite different from it, and which signifies lustre, brilliancy, especially the mild lustre of the moon; to express "shining mass,' moreover, in accordance with the spirit of the Qquechhua language, the position of the two words would have to be reversed, pacsaccotto.

31 Friedrich Hoffmann, in Poggendorff's Annalen, Bd. xxvi, 1832,

extended pumice quarries, four miles and a half from Lactacunga, present, according to my investigation of the local conditions, an analogy with this occurrence on Lipari. These quarries, in which the pumice-stone, divided into horizontal beds, has exactly the appearance of a rock in position, excited even the astonishment of Bouguer in 1737 32. "On volcanic mountains," he says, "we only find simple fragments of pumice-stone of a certain size; but at seven leagues to the south of Cotopaxi; in a point which corresponds with our tenth triangle, pumice-stone forms entire rocks, ranged in parallel banks of 5 to 6 feet in thickness in a space of more than a square league. Its depth is not known. Imagine what a heat it must have required to fuse this enormous mass, and in the very spot where it now occurs; for it is easily seen that it has not been deranged, and that it has cooled in the place where it was liquefied. The inhabitants of the neighbourhood have profited by this immense quarry, for the small town of Lactacunga, with some very pretty buildings, has been entirely constructed of pumice-stone, since the earthquake which overturned it in 1698."

The pumice quarries are situated near the Indian village of San Felipe, in the hills of Guapulo and Zumbalica, which are elevated 512 feet above the plateau and 9990 feet above the sea level. The uppermost layers of pumice-stone are, therefore, five or six hundred feet below the level of Mulalo, the once beautiful villa of the Marquis of Maenza (at the foot of Cotopaxi), also constructed of blocks of pumice-stone, but now completely destroyed by frequent earthquakes. The subterranean quarries are at unequal distances from the two active volcanoes, Tungurahua and

32 Bouguer, Figure de la Terre, p. lxviii. How often, since the earthquake of the 19th July, 1698, has the little town of Lactacunga been destroyed and rebuilt with blocks of pumice-stone from the subterranean quarries of Zumbalica! According to historical documents communicated to me during my sojourn in the country, from copies of the old ones which have been destroyed, and from more recent original documents partially preserved in the archives of the town, the destructions occurred in the years 1703 and 1736, on the 9th December, 1742, 30th November, 1744, 22nd February, 1757, 10th February, 1766, and 4th April, 1768,-therefore seven times in 65 years! In the year 1802 I found four-fifths of the town still in ruins in consequence of the great earthquake of Riobamba on the 4th February,

Cotopaxi: 32 miles from the former, and about half that dis-tance from the latter. They are reached by a gallery. The workmen assert that from the horizontal solid layers, of which a few are surrounded by loamy pumice fragments, quadrangular blocks of 20 feet, divided by no transverse fissures, might be procured. The pumice-stone, which is partly white and partly bluish gray, consists of very fine and long fibres, with a silky lustre. The parallel fibres have sometimes a knotted appearance, and then exhibit a singular structure. The knots are formed by roundish particles of finely porous pumice-stone, from 1-1 line in breadth, around which long fibres curve so as to inclose them. Brownish black mica in small six-sided tables, white crystals of oligoclase, and black hornblende are sparingly scattered in it; on the other hand, the glassy felspar, which elsewhere (Camaldoli, near Naples) occurs in pumice-stone, is entirely wanting. The pumice-stone of Cotopaxi is very different from that of the quarries of Zumbalica: its fibres are short, not parallel, but curved in a confused manner. Magnesia-mica, however, is not peculiar to pumicestone, for it is also found in the fundamental mass of the trachyte of Cotopaxi. At the more south rn volcano, Tungurahua, pumice-stone appears to be entirely wanting. There is no trace of obsidian in the vicinity of the quar33 This difference has also been recognized by the acute Abich, (Ueber Natur und Zusammenhang vulkanischer Bildungen, 1841, s. 83).

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34 The rock of Cotopaxi has essentially the same mineralogical composition, as that of the nearest volcanoes, Antisana and Tungurahua. It is a trachyte, composed of oligoclase and augite, and consequently a Chimborazo-rock: a proof of the identity of the same kind of volcanic mountain in masses in the opposite Cordilleras. In the specimens collected by me in 1802, and by Boussingault in 1831, the fundamental mass is partly light or greenish gray, with a pitchstone-like lustre and translucent at the edges; partly black, nearly resembling basalt with large and small pores, which possess shining walls. The inclosed oligoclase is distinctly limited; sometimes in very brilliant crystals, very distinctly striated on the cleavage planes; sometimes in small fragments and difficult of detection. The intermixed augites are brownish and blackish green and of very variable size. Dark laminæ of mica and black metallic grains of magnetic iron are rarely and probably quite accidentally sprinkled through the mass. In the pores of a mass containing much oligoclase, there was some native sulphur, probably deposited by the all-penetrating sulphurous vapours.