12 
HISTORY OF MADAGASCAR. 
pentine course from one side of the ravine to the other, 
now disappeared, and forced its way by a subterranean 
passage for at least a quarter of a mile. 
44 Fragments of rock thrown together in several places, 
formed a frightful bridge over the stream. Many of those 
masses were more than 100 feet in length, and generally 
presented a globular, or rather oval-shaped form. Some, 
again, presented massy sides and rather obtuse peaks, 
towering from the sides of the valley. Beneath and between 
these blocks of granite were extensive caverns, occasionally 
twelve or sixteen feet in breadth, connected by passages in 
some places so narrow as scarcely to allow a person to pass 
between them. These caverns received light through aper¬ 
tures between the stones by which they were formed, but 
in some places they were so dark and deep as almost 
to forbid the approach of those who were desirous of 
exploring them. We penetrated their gloom for a dis¬ 
tance of nearly two hundred yards, and might have gone 
much farther had time and strength permitted. The river, 
during the dry season, seemed to find a way considerably 
lower than the bottom of the caverns, for we neither saw 
nor heard any thing of it. But in the rainy season, that 
passage must be too small for the waters of the swollen 
stream: they must then rush with fearful violence through 
the passages we were now exploring. During that season, 
when generally the stream both above and below is impass¬ 
able, the projecting masses of rock are used as bridges by 
the natives, and afford means of communication between 
the opposite sides of the valley, more safe and easy than 
any other they could devise for crossing the torrents. 
64 On looking at those hills called Vava vato from the 
north, at a distance of ten or fifteen miles, they present a 
most rugged and irregular aspect, resembling an assem- 
