THEIR P1IEK0MENA. 
169 
propagation of the motion. Thus, in the mines of Saxony, 
we have seen workmen hasten up alarmed by oscillations 
which were not felt at the surface of the ground. 
If, in regions the most remote from each other, primitive, 
secondary, and volcanic rocks, share equally in the convul- 
sive movements of the globe ; we cannot but admit also that 
within a space of little extent, certain classes of rocks 
oppose themselves to the propagation of the shocks. At 
Cumana, for instance, before the great catastrophe of 1797, 
the earthquakes were felt only along the southern and cal- 
careous coast of the gulf of Cariaco, as far as the town of 
that name ; while in the peninsula of Araya, and at the village 
of Maniquarez, the ground did not share the same agitation. 
But since December 1797, new communications appear to 
have been opened in the interior of the globe. The penin- 
sula of A raya is now not merely subject to the same agita- 
tions as the soil of Cumana, but the promontory of mica- 
slate, previously free from earthquakes, has become in its 
turn a central point of commotion. The earth is sometimes 
strongly shaken at the village of Maniquarez, when on the 
coast of Cumana the inhabitants enjoy the most perfect 
tranquillity. The gulf ot Cariaco, nevertheless, is only sixty 
or eighty fathoms deep. 
It has been thought from observations made both on the 
continent and in the islands, that the western and southern 
coasts are most exposed to shocks. This observation is con- 
nected with opinions which geologists have long formed re- 
specting the position of the high chains of mountains, and 
the direction of their steepest declivities ; but the existence 
•of the Cordillera of Caracas, and the frequency of the oscil- 
lations on the eastern and northern coast of Terra Timm, 
in the gulf of Paria, at Carupano, at Cariaco, and at Cumana, 
render the accuracy of that opinion doubtful. 
In New Andalusia, as well as in Chile and Peru, the 
shocks follow the course of the shore, and extend but little 
inland. This circumstance, as we shall soon find, indicates 
an intimate connection between the causes which produce 
earthquakes and volcanic eruptions. If the earth was most 
agitated on tin; coasts, because they are the lowest part of 
the land, why should not the oscillations be equally strong 
