DtJ NOYElt — NOTES ON TITI? OFANT's OATIREWAY. 
0 
columnar bods ; tliey also iKioomo tliiniioi', and lose tlieiv I'oniarkablc 
parallolism of deposition, as well as distinct columnar structui'o ; 
Tlio upper one is now but rudely columnar, and the columns are 
much thicker than those of the bed below ; tlie underlying ochre- 
layer is wanting, and its place is supplied by a deposit of amorphous 
basalt, which now attains a thickness equal to that of the super- 
imposed columnar beds. This change of structure in the cHfi-section 
occurs in a distance of less than three hundred yards. Below 
this amorphous basalt a new columnar bed of trap appears, the 
pillars of which are exceedingly symmetrical in every respect, and of 
great beauty ; they arc exposed for the distance of about two hun- 
dred feet, and are all inclined to the eastwards ; while their uppei' 
surface, whicli is very even, slopes to the westward at about six 
to eight degrees. This group of columns is called " The Organ" 
(see figs. 4 and 5). 
Below this bed, though not absolutely seen, the missing ochre- 
layer is presumed to be. If we now follow the cliflF section west- 
ward, wo find that the " organ-bed" in its extension to that direction, 
and with its dip of six to eight dogi'ees would eventually be 
brought so low that more than one-half of its thickness would be 
emersed below the level of the sea, leaving the remainder to project 
above the water, and thus to form that singular looking natural pier 
called " The Giant's Causeway." At this spot the thickest and veiy 
nearly the most central portion of this particular lava-flow is reached, 
and it is worthy of remark that here the columns on the east side of 
the Causeway, which is about one hundi-ed and sixty feet across, in- 
cline to the east, while on the west side they slope to the west, thus 
showing in their vertical arrangement a radiation from a series of 
centres, all following a given line, which would have very nearly a 
meridional direction, or in other words that of the longest axis of 
the lava-flow. This structure, I have no doubt, would be apparent 
tlirougliout the entire of this particular bed if we had the power to 
examine it throughout, indeed the view which the cliffs afford of it 
is almost conclusive on this point, as it exposes a transverse section 
of it in two of its most impoi"tant positions, viz., at the " Organ-" 
columns, near its eastern termination, and at the Causeway, close to 
its centre. 
VOL. III. B 
