184 
PENINSULA OF ABAYA 
which might easily be confounded with real limestone, lies 
immediately over the mica-slate ; while on the opposite side, 
near Puuta Delgada, this sandstone covers a compact bluish 
gray limestone, almost destitute of petrifactions, and tra- 
versed by small veins of calcareous spar. This last rock is 
analogous to the limestone of the high Alps.* 
The very recent sandstone formation of the peninsula of 
Araya contains : — first;, near Punta Arenas, a stratified sand- 
stone, composed of very fine grains, united by a calcareous 
cement in small quantity secondly, at the Cerro de la Yela, 
a schistose sandstone, t without mica, and passing into slate- 
clay, J which accompanies coal : — thirdly, on the western side, 
between Punta Gorda and the ruins of the castle of Santiago, 
breccia composed of petrified sea-shells united by a calcare- 
ous cement, in which are mingled grains of quartz ; — fourthly, 
near the point of Barigon, whence the stone emploved for 
building at Cumana is obtained, banks of yellowish white 
shelly limestone, in which are found some scattered grains of 
quartz ; — fifthly, at Penas Negras, at the top of the Cerro de 
la Yela, a bluish gray compact limestone, very tender, almost 
without petrifactions, and covering the schistose sandstone. 
However extraordinary this mixture of sandstone and com- 
pact limestone § may appear, we cannot doubt that these 
strata belong to one and the same formation. The very 
recent secondary rocks everywhere present analogous phe- 
nomena ; the molasse of the Pays de Yaud contains a fetid 
shelly limestone, and the cerite limestone of the banks of the 
Seine is sometimes mixed with sandstone. 
The strata of calcareous breccia are composed of an infi- 
nite number of sea-shells, from four to six inches in diameter, 
and in part well preserved. We find they contain not am- 
monites, but ampullaires, solens, and terebratuke. The 
greater part of these shells are mixed : the oysters and 
pectinites being sometimes arranged in families. The whole 
are easily detached, and their interior is filled with fossil 
madrepores and cellepores. We have now to speak of a 
fourth formation, which probably rests || on the calcareous 
* Alpenkalkstein. 
t Sandsteinschiefer. J Thonschiefer. § Dichter kalkstein. 
II It were to be wished that mineralogical travellers would examine more 
particularly the Cerro de la Vela. The limestone of the Pefias Negras 
