262 Essay, @c, 
clining situation, and extend to the rivers bounda 
ing it in che East and West: the lavas project 
in some parts in connected groupes, like rocks 
of granite from primitive mountains, or they are 
thrown together in detached fragments; the 
intervening spaces being covered with a deep 
vegetable mould: their surface is either smooth, 
like that of Basaltes, or cellular like scorie: 
*In the river Datar, which I followed several 
hundred yards through various windings and 
small cascades, I found an extensive channel of 
compact lava, consisting, in many places, of a 
vertical height of 30 feet. 
Near its banks, an extensive fissureof one of 
j the ridges discloseda cavity about 30 feet deep, 
consisting likewise of compact lava, separating 
spontaneously into large, more or less deter- 
minate blocks, often with regular sides, the 
surface of which is cellular, and in many in- 
stances ofa reddish colour; the mass composing 
this eminence must be considered of anterior 
date, being covered by a thin stratum of rolled 
Basaltes of various sizes, mixed with sand and 
gravel. The stream in contact with this on the 
descent above mentioned, and probably also 
that which compos. the basin of the river 
Datar, exhibited the ces observed in 
our volcanoes ca recent eruptions ; 5 separate 
with adjoining groupes, more or less regular, 
approaching the nature of Basaltes. are often 
ex ibited. as hast : i ja her plac 
E Cat No. 33. 
t Exp. Cat. No. 32. 
