306 In the Upper Sierra 
nest of a Bearded Vulture. Kestrels are, as might be expected, 
ubiquitous as also are Rock Doves. 
The higher summits of these limestone mountains are composed 
of a series of pinnacles of horizontal strata much weathered, as can 
be seen by the accompanying photograph of the summit of the 
sierra near Jimera. This was taken at a height of about 4,100 ft. 
A SUMMIT IN THE SERRANIA DE RONDA. 
(Carboniferous limestone.) 
One of the largest of these desolate stony hills is the Sierra de 
Libar which rises to considerably over 5,000 ft. For many miles 
around, its white stony surface bare of any herbage, dominating 
this portion of the sierras can be singled out from among the sea 
of surrounding mountains. On most sides it is scarped by preci- 
pices or by steep slopes of broken rocks fallen from above, making 
access to its higher parts difficult and toilsome. A few rarely used 
