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- 



