of the Counties of Derry and Antrim . 203 
equally grand; and similar abruptions, or sections (though 
not so deep) are scattered over a great part of our area, and 
especially on the ridges of our hills and mountains which are 
cut down in many places like a stair, by the sudden abrup- 
tion of the basaltic stratum. 
9. Wherever the strata are thus suddenly cut off', whether 
it be a mass of accumulated strata as in the facades on our 
coast, or solitary strata in the interior ; the materials on one 
side of the abruption are completely carried away, without 
a fragment being left behind, while on its other side the un- 
touched stratum remains intire and undisturbed. 
I shall not proceed to apply these facts to support, or in- 
validate, any of the numerous theories which have given rise 
to so much controversy, in which I myself (as you know) 
have borne some part ; I shall look to nature alone, without 
much reference to opinions, and shall endeavour to trace, by 
the marks she has left behind her, some of the grand opera- 
tions she once executed on the surface of our globe. 
Varro divided the time elapsed since the beginning of the 
world into three portions, which he distinguished by the 
names, prolepticum , fabulosum , and historicum . 
The first comprehended the period of absolute darkness ; in 
the second some faint lights were thrown upon the history of 
its events, by fable and tradition ; in the third, the historian 
had the common aids from which history is usually compiled. 
The natural history of the world seems to admit of a cor- 
responding division. In the first I include the formation of our 
strata, their induration, their derangement from the horizontal 
position in which they seem originally to have been placed 4 
D d 2 
