172 
THE UPPER AMAZONS. 
Chap. III. 
dread of the " terras cahidas/' or landslips^ which occa- 
sionally take place along the steep, earthy banks ; espe- 
cially when the waters are rising. Large vessels are 
sometimes overwhelmed by these avalanches of earth 
and trees. I should have thought the accounts of them 
exaggerated if I had not had an opportunity during this 
voyage of seeing one on a large scale. One morning I 
was awoke before sunrise by an unusual sound resem- 
bling the roar of artillery. I was lying alone on the top 
of the cabin ; it was very dark, and all my companions 
were asleep, so I lay listening. The sounds came from 
a considerable distance, and the crash which had aroused 
me was succeeded by others much less formidable. The 
first explanation which occurred to me was that it was 
an earthquake ; for, although the night was breathlessly 
calm, the broad river was much agitated and the vessel 
rolled heavily. Soon after, another loud explosion took 
place, apparently much nearer than the former one ; 
then followed others. The thundering peal rolled back- 
wards and forwards, now seeming close at hand, now far 
off ; the sudden crashes being often succeeded by a pause 
or a long-continued dull rumbling. At the second 
explosion, Vicente, who lay snoring by the helm, awoke 
and told me it was a terra cahida ; " but I could 
scarcely believe him. The day dawned after the uproar 
had lasted about an hour, and we then saw the work of 
destruction going forward on the other side of the river, 
about three miles off. Large masses of forest, including 
trees of colossal size, probably 200 feet in height, were 
rocking to and fro, and falling headlong one after the 
other into the water. After each avalanche the wave 
