Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

ISQi. CLIFFS OF EAETH PROGRESS — LAVA. 347 daybreak, and until after sunrise, the river was smoking, quite as if it were boiling. This day we passed some earthy cliffs between two and three hundred feet in height, and where they came in our way it was extremely difficult to manage the boats and tow-lines ; but by veering out at those times a great length of rope, our object was accomplished without any disaster. Near these cliffs the valley of the river begins to contract and become more irregular, and the sides or breaking down of the higher ranges become more abrupt and are nearer to the river. In most places we found a cliffy side opposite to a low pro- jecting point of shingle, but in some spots that we passed both sides were high, and we had no choice on which to take the tow-line. The difference, also, between the level of the higher ranges and that of the river, was observed to be much increased. On this day (25th) our best shots succeeded in killing two guanacoes, but they died out of our reach, and probably became food for pumas, instead of man. The order of our march was usually one or two riflemen in advance, as scouts — Mr. Darwin, and occasionally Mr. Stokes, or Mr. Bynoe, upon the heights — a party walking along the banks, near the boats, ready to reheve or assist in tracking, and the eight or ten men who were dragging the three boats along at the rate of about two miles an hour over the ground, though full eight knots through the water. Difficult places to pass — delays caused by embarking and disembarking frequently to change banks, and avoid impediments — the necessary observa- tions, rest, and meals, occupied so much time that we did not average more than twelve miles in one day : and even that small distance was not accomplished without making both slioulders and feet sore. 26th. In the distance some very level topped, dark looking cliffs, were seen at the summits of elevated ranges, which Mr. Darwin thought must have a capping or coating of lava. Of course we were very anxious to verify a fact so curious, and at noon were quite satisfied that it was so, having approached to the foot of a height thus capped, whose frag-