GEOLOGY. 
103 
calcareous marl also near D, I met with silicified wood; and between the carbonaceous 
and marly strata, crystals of sulphate of iron. 
The coast from Lirquen Head to Punta Parra is without variation, composed of 
alluvium at the summit, compact grey marl in the middle, and clay-slate at the base. 
On the north of Punta Parra, at the cliffs marked G, H, and I, the upper stratum is 
alluvial ; the next slaty marl and loose earthy sand-stone, containing balls of compact 
marl, aud enclosing fossil dicotyledonous wood, shells, and bones. The wood is some- 
times converted to black jasper, and sometimes to carbonate of lime ; it is also perfo- 
rated by a teredo, the perforations being filled with crystallized carbonate of lime, as in 
the fossil-wood of the London clay. The third stratum is compact marl. 
On the north of I is a sandy beach, with a long valley extending to the river 
Caracol : at this river the sand is chiefly magnetic iron, and had considerable effect on 
the compass. The iron sand is chiefly on the surface of a very fine siliceous sand, and 
in some places where it had caked by the sun, I found it unmixed of four and six inches’ 
depth. Similar sand occurs also on the beach near Penco, and on the south end of the 
Island of Quiriquina, and other parts of the bay. The shore from the Caracol to Tome 
Head is sandy, with a slight mixture of mica ; and the cliffs are chiefly of clay-slate. 
Immediately north of Tome Head is a sandy beach, with clay-slate inland. At the 
cliff marked L, the marly strata recommence. 1. The superstratum alluvial. 2. Loose 
quartzy sand. 3. Blue clay approaching fullers’ earth. 4. Bed marl, with balls of cal- 
careous marl and beds of hard sand-stone, inclination 15°, dipping north. In this cliff 
found numerous petrifactions, and two vertebrae about the size of those of an ox, (these 
have been lost:) also a large ammonite, measuring two feet ten inches in diameter, but 
too heavy to be removed ; and some fossil-wood converted into coarse jasper, and con- 
taining veins and nodules of chalcedony. In one specimen the small longitudinal vessels 
of the wood were filled with iron pyrites. At the northern extremity of the section, the 
vertical slate rocks which form the base of Point Darca are divided from the sand-stone 
and alluvium of the hills above and behind it, by a mass of green porphyry and horn- 
stone ; and on the surface of this porphyry is a bed of porphyritic pebbles, about a hun- 
dred feet above the level of the sea. — B. 
VALPARAISO. 
The lower hills around Valparaiso rise by abrupt and rocky cliffs from the sea-coast; 
and on both sides of the bay, as well as behind the town, the granite shews itself. But 
in the head of the bay the country rises gradually at first in a verdant slope, and after- 
wards by a more rapid ascent. The road which passes over this ridge to Santiago is in 
some places very steep, on a diluvial formation containing numerous boulders. The 
surface of these hills is bare in many places, and shews large red patches of soil. — C. 
SALAS-Y-GOMEZ ISLAND. 
This island is three-quarters of a mile long, and about thirty feet high. It is com- 
posed of a dark-coloured rock, having a reddish brown tint where it is washed by the 
sea. The cliff is perpendicular for some feet at the water’s edge, whilst the interior is 
