FORCHHAMMER ON THE FORMATION OF DOLOMITE. 53 



bular masses were formed in any other manner than that m which 

 the Karlsbad pea-stone, confetti di Tivoh, and all similar formations 

 comprised under the term Roe-stone [Rognstenen], originated. 



This is brought about by water in one or two ways ; it separates 

 and brings up small particles, around which lime, disengaged by the 

 escape of the carbonic acid, is deposited. As long as these separate 

 particles remain washed about in the water, they must naturally be 

 round, as the isolation is perfect on all sides ; but when they ultimately 

 become so heavy that the v/ater cannot keep them in a state of mo- 

 tion and therefore floating, they sink downwards and become united 

 by means of the disengaged lime into connected masses. The for- 

 mation at Karlsbad takes place in the same manner ; and the only 

 variation in the form of the two deposits is, that the Karlsbad piso- 

 lite has a conchoidal fracture, which is never found in the dolomite 

 spheroids of Faxoe, nor in that from Fullwell near Sunderland. But 

 there is the great diiference at Karlsbad and the other places men- 

 tioned, that at the former the spring has a subaerial outlet, whilst 

 the others had submarine outlets ; and it is natural that in the first 

 case far more numerous interruptions must occur, as expressed by 

 the conchoidal fracture, than in the last, where the great body of 

 water must make the separations far m.ore regular. 



It results from the foregoing, that the size of the spheroids is a 

 measure of the force of the springs ; and, for comparison, I will here 

 remark, that the fountain at Tostrup Valdbye, giving 13,000 tons 

 of water per diem from a bore of 6 inches diameter, could keep 

 suspended a fragment of limestone weighing a pound. The spring- 

 pipes at Faxoe have on an average a diameter of at least double this, 

 and their current of water must have been at least four times as 

 strong to have supported the floating dolomite masses of a pound 

 weight. I may also add, that the globular bodies, formed by sub- 

 marine springs, are easily distinguished from those arising from 

 trituration (Roe-stone) ; the former are of unequal size on account of 

 the very unequal motion in and near the spring-head ; whilst the 

 trituration eff'ected by the waves is uniform. Its form and mode of 

 arrangement distinguish the Faxoe dolomite as having been the result 

 of a submarine spring ; and as the underlying Faxoe limestone is a 

 marine formation, and the calcareous sand, in which the dolomite 

 occurs, contains marine corals, and the limestone that surmounts the 

 whole is likewise marine, it is impossible to entertain a thought of 

 these springs having been extra-marine. 



It could scarcely be supposed that the springs would have had 

 their issue at the top of the hill, and not, as now, at the foot ; but 

 on a closer examination of the various conditions, it will be evident 

 that the springs must have burst from the top of the hill, as appears 

 from the spring-pipes that they occupied. We imagine that fresh 

 water penetrated the Faxoe Hill when the sea still covered the whole 

 formation ; and, therefore, that the place, where the springs would 

 issue, would be determined by the greater or less resistance opposed 

 to them. At present the least resistance is where the springs break 

 out at the base of the hill, the counter-pressure there being the at=» 



