47 
Unfortunately the pilot has never yet been taught to consider the 
chemical or mineralogical character of the substances, which he 
brings from the bottom of the sea, so that it is not easy to conjec- 
ture what is meant by the descriptions he gives; but, with the last 
idea in view, I think much light may be thrown on the subject, and 
hereafter we may hope for more distinct information and a better 
nomenclature. 
If what I am now about to state be confirmed by future observa- 
tion, the position of the Navigator a hundred miles at sea may be 
as certainly ascertained by sounding as if he was within sight of 
land. 
It is agreed on all hands, that, if there be any thing tolerably 
certain in Geological science, it is, that the component rocks of the 
globe follow a certain order of position with respect to each other : 
that, for example, the chrystallized granitic rocks are the lowest, 
followed by the slaty, whether micaceous or argillaceous ; that 
these are covered by the conglomerate sandstone beds, this again 
by the limestone, that by sandstone and coal, and the coal measures 
are again covered by other horizontal strata of various kinds, viz. 
red marl, oolites, chalk, &c. of which, though they constitute the 
chief strata in the east of England and in France, we have few exam- 
ples in this country, and therefore they need not be here particularized. 
Now observe, that the strata of the west of France and Kng- 
land are primary, viz. granite and slate; those of Wales and the 
south of Ireland, slate, conglomerate, and coal; and that, for a 
great way up the channel, we need expect to find nothing higher in 
the series of strata. 
When we look at the western edge of the bank of soundings, we 
find it described as fine white sand, 7. e. quartz ; white sand with 
black specks, 7. e. quartz with mica; and, along the south edge, 
VOL. XIV, K 
