Observations on the Rate at which Stalagmite is being accumulated in the Ingleborough Cave. Proceed. Lit. and Phil. Soc. Manch. April 1873.

The only attempt to measure with accuracy the rate of the accumulation of stalagmite in caverns, in this country, is that made by Mr. James Farrer in the Ingleborough Cave, in the years 1839 and 1845, and published by Prof. Phillips in the “Rivers, Mountains, and Sea Coast of Yorkshire” (second edition, 1855, pp. 34–35). The stalagmite of which the measurements were taken is that termed, from its shape, the Jockey Cap. It rises from a crystalline pavement to a height of about two and a half feet, and is the result of a deposit of carbonate of lime, brought down by a line of drops that fall into a basin at its top, and flow over the general surface. On March 13th, 1873, in company with Mr. John Birkbeck and Mr. Walker, I was enabled by the kindness of Mr. Farrer to take a set of measurements, to be recorded for use in after years.

For the sake of insuring accuracy in future observations, three holes were bored at the base of the stalagmite, and three gauges of brass wire, gilt, inserted; gauge No. 1 in the following table being that on the S.S.E., No. 2 on N.N.E., No. 3 on the West side. The curvilinear dimensions were taken with fine iron wire, or with a steel measure; and the circumferential around the base along a line marked by the three gauges. The measurements 2, 3, and 4 of the table were taken on the 15th of March, by Mr. Walker, and their accuracy may be tested by the fact that they coincide exactly with No. 1, which I took two days before.

The lengths of wire, properly labelled, are deposited in the Manchester Museum, the Owens College, for future observers.

In the following table I have given my own measurements and compared them with those taken by Mr. Farrer.

TABLE OF MEASUREMENTS.

Unfortunately I have been unable to identify the exact spots where the stalagmite was measured by Mr. Farrer, so that the only measurement which affords any trustworthy data for estimating the rate of increase is number 14. With regard to this, the only possible ground of error is the erosion of the general surface of the solid limestone, of which the roof is composed, by carbonic acid, since the year 1845, and this is so small as to be practically inappreciable. We have, therefore, evidence that the Jockey’s Cap is growing at the rate of ·2946 of an inch per annum, and that if the present rate of growth be continued it will finally arrive at the roof in about 295 years. But even this comparatively short lapse of time will probably be diminished by the growth of a pendent stalactite above, that is now being formed in place of that which measured ten inches in 1845, and has since been accidentally destroyed. It is very possible that the Jockey Cap may be the result not of the continuous but of the intermittent drip of water containing a variable quantity of carbonate of lime, and that, therefore, the present rate of growth is not a measure of its past or future condition. Its possible age in 1845 was estimated by Prof. Phillips at 259 years, on the supposition that the grain of carbonate of lime in each pint was deposited. If, however, it grew at its present rate it may be not more than 100 years old. All the stalagmites and stalactites in the Ingleborough Cave may not date further back than the time of Edward III. if the Jockey Cap be taken as a measure of the rate of deposition.