A to Z Classics - Bram Stoker - The Complete Novels

“Not the least in the world. It will be a real pleasure to have such a good listener. To begin at the beginning, I was much struck with that old cavity on the top of the Hill. It is one of the oddest things I have ever seen or heard of. If it were in any other place or among any other geological formation, I would think its origin must have been volcanic. But here such a thing is quite impossible. It was evidently once a lake.”

“So goes the legend. I suppose you have heard it?”

“Yes; and it rather confirms my theory. Legends have always a base in fact; and whatever cause gave rise to the myth of St. Patrick and the King of the Snakes, the fact remains that the legend is correct in at least one particular — that at some distant time there was a lake or pond on the spot.”

“Are you certain?”

“A very cursory glance satisfied me of that. I could not go into the matter thoroughly, for that old wolf of mi ne was so manifestly impatient that I should get to his wild-goose chase for the lost treasure-chest, that the time and opportunity were wanting. However, I saw quite enough to convince me.”

“Well, how do you account for the change? What is your theory regarding the existence of limestone?”

“Simply this, that a lake or reservoir on the top of a mountain means the existence of a spring or springs. Now, springs in granite or hard slate do not wear away the substance of the rock in the same way as they do when they come through limestone. And, moreover, the natures of the two rocks are quite different. There are fissures and cavities in the limestone which are wanting, or which are, at any rate, not so common or perpetually recurrent in the other rock. Now, if it should be, as I surmise, that the reservoir was ever fed by a spring passing through a streak or bed of limestone, we shall probably find that in the progress of time the rock became worn, and that the spring found a way in some other direction — either some natural passage through a gap or fissure already formed, or by a channel made for itself.”

“And then?”

“And then the process is easily understandable. The spring naturally sent its waters where there was the least resistance, and they found their way out on some level lower than the top of the Hill. You perhaps noticed the peculiar formation of the Hill, specially on its west side — great sloping tables of rock suddenly ended by a wall of a different stratum — a sort of serrated edge all the way down the inclined plane; you could not miss seeing it, for it cuts the view like the teeth of a saw! Now, if the water, instead of rising to the top and then trickling down the old channel, which is still noticeable, had once found a vent on one of those shelving planes it would gradually fill up the whole cavity formed by the two planes, unless, in the mean time, it found some natural escape. As we know, the mountain is covered in a number of places with a growth or formation of bog, and this water, once accumulating under the bog, would not only saturate it, but would raise it — being of less specific gravity than itself — till it actually floated. Given such a state of things as this, it would only require sufficient time for the bog to become soft and less cohesive than when it was more dry and compact, and you have a dangerous bog, something like the carpet of death that we spoke of this morning.”

“So far I can quite understand,” said I. “But if this be so, how can the bog shift as this one undoubtedly has? It seems, so far, to be hedged with walls of rock. Surely these cannot move.”

Sutherland smiled. “I see you do apprehend. Now we are at the second stage. Did you notice, as we went across the hill-side, that there were distinct beds or banks of clay?”

“Certainly; do they come in?”

“Of course. If my theory is correct, the shifting is due to them.”

“Explain!”

“So far as I can. But here I am only on surmise, or theory pure and simple. I may be all wrong, or I may be right — I shall know more before I am done with Shleenanaher. My theory is that the shifting is due to the change in the beds of clay, as, for instance, by rains washing them by degrees to lower levels; this is notably the case in that high clay bank just opposite the Snake’s Pass. The rocks are fixed, and so the clay becomes massed in banks between them, perhaps aided in the first instance by trees falling across the chasm or opening. But then the perpetually accumulating water from the spring has to find a way of escape; and as it cannot cut through the rock, it rises to the earth bed, till it either tops the bed of clay which confines it or finds a gap or fissure through which it can escape. In either case it make a perpetually deepening channel for itself, for the soft clay yields little by little to the stream passing over it, and so the surface of the outer level falls, and the water escapes, to perhaps find new reservoirs ready-made to receive it, and a similar process as before takes place.”

“Then the bog extends, and the extended part takes the place of the old bog, which gradually drains.”

“Just so; but such would, of course, depend on the level; there might be two or more reservoirs, each with a deep bottom of its own and united only near the surface; or if the bank or bed of clay lay in the surface of one shelving rock, the water would naturally drain to the lowest point, and the upper land would be shallow in proportion.”

“But,” I ventured to remark, “if this be so, one of two things must happen: either the water would wear away the clay so quickly that the accumulation would not be dangerous, or else the process would be a very gradual one, and would not be attended with such results as we are told of. There would be a change in the position of the bog, but there would not be the upheaval and complete displacement and chaos that I have heard of, for instance, with regard to this very bog of Knockcalltecrore.”

“Your ‘if is a great peacemaker. If what I have supposed were all, then the result would be as you have said; but there are lots of other supposes; as yet we have only considered one method of change. Suppose, for instance, that the water found a natural means of escape — as, for instance, where this very bog sends a stream over the rocks into the Cliff Fields — it would not attack the clay bed at all, unless under some unusual pressure. Then suppose that when such pressure had come the water did not rise and top the clay bed, but that it found a small fissure part of the way down. Suppose there were several such reservoirs as I have mentioned — and from the formation of the ground I think it very likely, for in several places jutting rocks from either side come close together, and suggest a sort of gap or canon in the rock formation, easily forming it into a reservoir. Then, if the barrier between the two upper ones were to be weakened and a sudden weight of water were to be thrown on the lower wall, suppose such wall were to partially collapse, and bring down, say, a clay bank, which would make a temporary barrier loftier than any yet existing, but only temporary; suppose that the quick accumulation of waters behind this barrier lifted the whole mass of water and slime and bog to its utmost height. Then, when such obstruction had been reached, the whole lower barrier, weakened by infiltration and attacked with sudden and new force, would give way at once, and the stream, kept down from above by the floating bog, would force its way along the bed-rock and lift the whole spongy mass resting on it. Then, with this new extent of bog suddenly saturated and weakened — demoralised as it were — and devoid of resisting power, the whole floating mass of the upper bog might descend on it, mingle with it, become incorporated with its semi-fluid substance, and form a new and dangerous quagmire incapable of sustaining solid weight, but leaving behind on the higher level only the refuse and sediment of its former existence — all the rubble and grit too heavy to float, and which would gradually settle down on the upper bed-rock.”