PARISH OF TEMPLEMORE. 
of Shantallow, and the bog and lake of Ballyarnet, a chain of isolated sand-hills may be traced, ap¬ 
pearing above the bog, while, opposite to one of them, a remarkable pinnacle of rock also rises above 
its surface, and another, at no great distance, is seen just level with it. Up the sides of these sand¬ 
hills the bog is seen to have crept, and, as within the memory of the existing generation it has 
covered the summits of some of them, no doubt can exist that the sand-hills were prior in origin 
to the bog. In the still more marked depression, which, constituting the valley of Pennyburn, 
proceeds with little variation of level towards Lough Swilly, the appearances are equally illustrative; 
for, in advancing towards the W., the valley is narrowed between two beds, or islands, of rocks, 
and'exhibits a channel so natural and well-defined that it is impossible to resist the feeling of being- 
in a river, or strait—an effect which is greatly heightened by the level, smooth, and now grassy 
bog, which lines the bottom. The channel again swells into an open basin, and is again for a 
short distance contracted, us it winds round some projecting rocks, which, like those previously 
described, seem to attest by their isolated position, limited extent, and low level, that some powerful 
agent, such as water, had long exercised on them its abrading influence. 
The curious sand-hill in the county of Donegal, called Dunberry Hill, is in the prolonga¬ 
tion of this valley, and bears the same relation to it, which those described in the preceding para¬ 
graph bear to the valley of Ballyarnet. Similar appearances are observable in the bog of Mul- 
lennan, which occupies the south-eastern corner of the parish, and extends beyond it—for there 
also the edge of the bog is marked by heaps or banks of sand, whilst Conn’s Hill rises like 
an island from its surface. 
As yet no shells, either fresh-water or marine, have been found in the detritic gravel, 
or clay, of this parish. In other parts of Ireland marl, abounding in fresh-water shells, is 
frequently the substratum of the smaller bogs, establishing fully their former lacustrine state, 
which is further supported by the occasional discovery of ancient canoes within them. Under 
the larger bogs clay, or gravel, without shells, is more commonly found ; but, before the full 
bearing of this deficiency on the question of formation can be estimated, the bottoms of existing 
lakes should be carefully examined in all positions, and under all circumstances, and the 
abundance, scarcity, or total absence, of shells in the shingle of the present sea or lake shores, 
carefully ascertained at various points, and under varying conditions. Indeed, as regards this 
immediate parish, the insulated valley of Derry, or Mary Blue’s Burn, seems a stepping-stone 
in the inquiry, as it can be nearly proved from history to have been a channel of the river ; and 
yet it still exhibits a bottom of gravel and clay, without shells—a circumstance in some measure 
to have been expected, as the current running through it was probably strong enough to 
render it an unfavourable habitation for molluscous animals. At present, therefore, the subject 
must be considered strong in the evidence of external characters, though, as yet, only partially 
supported by that of existing organic remains. 
That this valley has probably been a ■ water-course, may be judged from the following exca¬ 
vations :— 
F. I. 
1st. Excavation, 2 6—Surface loam, with pebbles of mica slate, and quartz. 
2nd. Excavation, 2 8—The same result as in the 1st; then bluish tenacious clay, with 
thin gravel. 
3rd. Excavation, 2 12—The same result as in the 1st and 2nd, then coarse gravel. 
Underneath there was a finer gravel mixed with sand. 
Boulders of primitive greenstone, and of granite, are occasionally found in the parish : 
they are of considerable size, and sometimes rest on other more minute detritus, as may be 
seen at a bluff, facing the valley which extends from Pennyburn to Lough Swilly. There are 
several on the shore of the Foyle, and at Culmore there is also a single boulder of basalt. 
SPECIFIC GRAVITIES. 
Variety 1. Mica slate, passing into gneiss .. .. .. 2.65 
Variety 2. Mica slate, passing into clay slate .. .. . . 2.84 
Variety 3. Mica slate, passing into quartz slate . . . . 2.69 
Greenstone .. .. .. .. .. .. 3.075 
It is usual to introduce geological descriptions by some notice of the physical features of the 
country, but such is more naturally placed at the close. 
The direction of the successive ridges of schist is nearly E. and W. These, as will have 
been seen from the preceding notice of “ Hills,” have disposed the country in a series of 
longitudinal valleys, which, from the tendency of slate rocks to break down on the outcropping 
side into slopes similar to that of the strata, are bounded on both sides by planes of nearly equal 
