21 6 Dr. Richardson’s Letter on the basaltic Surface. 
eighteen miles from the sea, and twenty-five miles along the 
coast, but now interrupted by the valley of the Mayo/a, like 
our former more diminutive interruptions, and also like them 
resumed at the next elevation, in the same rectilineal course, 
the strata preserving the same order, and the same charac- 
teristic marks. Or whether these strata, appearing on the 
summit of Slievegallon, be the commencement of a new ar- 
rangement, abandoned by nature as soon as begun : which is 
highly improbable, for neither limestone nor basalt are to be 
found on the mountain except in this solitary hummock. 
We might, by a minute attention to the inclinations, and ar- 
rangements, of the strata contiguous to the other interruptions 
I have enumerated, prove in like manner that the basaltic 
masses crowning the summits of the surrounding hills and 
mountains, are merely the remnants of strata once extensive 
and continuous, but interrupted and carried off, as in the pre- 
ceding case, by the same powerful agent. 
The more diminutive inequalities scattered over the whole 
surface of our area, and always produced by interruptions of 
the strata, would still more easily admit the appplication of 
the same reasoning, from the contiguity of their abrupted 
parts ; but the detail would be tedious ; those who wish to 
pursue the subject farther must come to the scene them- 
selves. 
Materials completely carried off. 
A circumstance perhaps still more extraordinary, is the 
complete removal of all the materials that once filled up the 
intervals between the abrupted parts of these strata ; I have 
stated in my £th fact, that the materials that had formerly 
