lot 
THE GEOLOGIST. 
what Mr. Selw^n lias advanced ; but tlie last ground I worked in on that lead 
being the outermost, or nearest the side of the lead, I again sunk through the 
black drift, lierc twenty-live feet thick, containing blackened wood and the 
cones of the "honeysuckle" (Baiilaia), and "bottomed" in a stratum of stiff 
bluish-grey clay, with very large boulders, which stratum was four feet thick. 
I expect the Spring Gully black drift and the drift of the black lead are of the 
same age, as the Spring Gully course has been traced to witlmi a short dis- 
tance of the black lead, which I conceive to have been the main watercourse of 
that period ; indeed, the number of smaller tributary leads of dark colo\ir join- 
ing it, in the same way that small streams now fall into larger ones, woidd in- 
dicate that such was the case. Here also the course of dark drift may be 
easily traced by the black heaps at the surface in striking contrast to the heaps 
on each side. In following down the black lead we reach Slaiighteryard Hill, 
where the evidence at first may not appear so conclusive, but where, if the 
facts are carefully weighed, they wiU I think, be found to support the former. 
Standing on the level of the present Cresswick Creek, looking north north- 
west, Slaughteryard Hill presents a steep escarpment of basalt, which has pi-o- 
bably come from the north, as northward the basaltic plateau extends some 
miles. Southward it does not exceed two hundred yards, thinning out very 
rapidly. Within one hundred and fifty yards are tlu'ce leads — the eastern, 
called llie black ; the middle, known as the white ; and the western lead the 
red streak — as far as had been determined at the time I left (1857) iiinuiug 
Sarallel ; all three running from south to north ; all three ovei'flowed by the 
asalt ; and all three above one hundred feet deep ; the deepest being the 
western, i. e., the red streak. 
Supposing, for the sake of argument, that the black, which is also the 
shallowest, is the oldest, we have a period no doubt, judging from tlie thick- 
ness of the deposit (twenty-five feet), extending over a considerable time, cha- 
racterized, it would appear from the vegetable remains, by extensive and long- 
continued conflagrations, succeeded by others, in which the utter absence of all 
igneous appearances prevails, succeeded in turn by an igneous outburst, cover- 
ing many square miles, with a basaltic overflow. On the other hand, take as 
the oldest the red streak — the deepest first, the white follows under certain 
modifications ; then, when we reach the period of the black drift, and igneous 
forces come into operation, it does not call for a great stretch of imagination to 
suppose that the period was consummated by a grand outburst and overflow of 
basalt. I am aware that m " SUuria," p. 492, Sir R. Murchisou and others 
account for the charred appearance of the vegetable matter, by showing that 
such matter is charred and destroyed in situ by the basalt ; however true that 
may be in other cases, I venture to think that had those eminent geologists 
seen the vegetable matter in Spring Gully, where there is no basalt, or other 
igneous rock, or the evidence that tlierc ever had been such, they would have 
seen the inapplicability of the reasoning in this instance. The black lead also is 
black a great way above, that is, much further south than the basalt. lu 
writing the above I do not impugn the accuracy of the observations made by 
Mr. SelwTO and others, I simply desire to record what I myself observed in 
the localities I speak of. I never worked elsewhere, and therefore tliese de- 
tails are purely local ; still, if true, the stratiim containing the vegetable matter 
is not the oldest. — I am, sir, yours truly, W. J. Morgan, Carmarthen. 
