36 ETNA. [Ch, XXVI. 



of the current a a is exposed to view as sTiown in the 

 diagrams, figs. 87 and 88. It is evident tliat Avhen tlie lava 



Highly inclined lava of Cava Grande. From a sketch made October 1857. 



a, a. Main stream of lava of 1G89 flowing 



eastward. 



a', a'. Branch of the same lava cascading 

 northwards into the ravine called the Cava 

 Grande, with a mean inclination of 35°. 



b, Section of upper or scoriaceous part of 

 the current, 6 feet thick. 



c, c. Solid layer of stony lava from SJ to 5 



"O 



feet thick, inclined at an angle of 35° and at 

 its upper extremity at 4 



d. Scoriaceous hecis forming the base of the 

 stream a', a', and underlying the stony layer c. 



e,/. ClifE containing 10 ancient lava currents 

 of Etna, appearing horizontal, but being in 

 fact inclined at 7° to the east, or towards the 



sea. 



readied tlie edge of the precipice, fragments of the solid 

 crnst with much loose scorise first rolled down, producing a 

 talus by vfhich the general slope of the cliff was reduced to 



!^JX.J2 ^ 



Fix. 88. 



Supposed north and south section of the rocks at the Cava Grande near the hea 



&•' 



V 



i^ 







all? 



ro 



or 



0" 







a 



actioii 

 ofEtD 



This ( 

 place : 

 a sea; 

 snoNV. 

 . great 

 king 

 catas 

 mont 

 tliee] 

 stills 

 depth 



The 

 at 16, 



rate o 

 miles. 



existiii 

 ill lenc 



niade i 



of tlio ravine. 



a, a. Lava of 1C89 with lofty parallel east 

 and west ridges. 



b, c, cJ, e, f. Same as in fig. 87. 



