4Q 



GEOLOGY OP MADEIRA. 



another ; the stratum exposed was 30 or 40 feet in depth, 

 and appeared to godown to the bottom of the hill. 

 Ccwst to the We also examined the coast to the weetward of the town 



i«Pit of ^,f Funchal. From the beach before the town to lllhoo 



Castle, and beyond it to the land called the Punta de fa 

 Cruz, the general character of the coast is as follows : the red 

 stone is the apparent base upon which rests a bed of gray pris- 

 matic lava, the stratum being sometimes from 40 to lOufeetin 

 depth. At times this gray lava rests upon a deep bed of ashes 

 and pumict, agglutinated together like the peperino and puz- 

 zofano in the vicinity of Naples. The scoria at the surface 

 is remarkably thick, and all the ujjp^r parts of the lava ap- 

 pear to be cellular. The general dip of the lava on the coast 

 near Funchal is to the north, but near the fort of lllhoo, it 

 forms with a mass of pumice, that is intersected with slight 

 veins of carbonate of lime and zeolite, a rapid angle or curve 

 of dechnation to the east. To the westward of the fort the 

 lava is not found for a little distance, and there is nothing 

 but deep beds of pumice and the agglutinated mass above- 

 mentioned. These beds of pumice are of varions thickness, 

 the deepest appearing to be about 4 feet, and alternating 

 with that stratum which I have called peperino. In dif- 

 ferent cavities of the pumice bed, there are large deposits of 

 black ashes. Toward the extremity of the strata the red 

 stone appears on the surface in a more solid state, and lies 

 in prismatic masses, the prisms being small, and not exceed- 

 ing a few inches in diameter. Their substance is brittle 

 and crumbles with ease. This stratum of red lava is of a 

 short continuance. Passing a small brook, it dips rapidly 

 to the westward, and in its place, the gray lava is found in a 

 confused though sometimes prismatic form, and rises from 

 the beach while the red lava still runs along the surface to 

 the height of near 100 feet, the top being covered with a 

 thick scoria. 

 Cascade to the There is also in the vicinity of Funchal, to the eastward 

 ^''^'* of the town, a fall of water, which, independent of the ro- 



mantic beauty of the situation, merits being visited on ac- 

 count of the exposure of the two strata of lava in their relative 

 position. Tiie hills are composed wholly of lava, some- 

 times of a prismatic formation, the red and gray lavas being 



visible 



