230 On the Occurrence of Nairo-horo-calcite in Gypsum. 



nn anticlinal ridge. Another section copied loosely in the front- 

 ispiece to mj work on volcanos, from Yon Buch's paper on the 

 Tyrol, may show the mode in which I conceive this to have oc- 

 curred through the injection of a mass of crystalline matter into 

 a wedge-shaped fissure, opening downwards; such as must have 

 frequently occurred among the fractures of the overlying strata 

 — o'ivinc^ occasion in some cases to the further rise of the heated 

 and intumescent matter into the hollow between the outer slopes 

 of the synclinal valley. It would indeed accord with the theory 

 suggested above, if such dykes or extravasations at synclinal 

 axes were found to alternate frequently with the elevated anti- 

 clinal axes, for the cracks formed in indurated beds of overlying 

 rock would very frequently open alternately upwards and down- 

 wards. 



Time will not allow of my dwelling now upon other points 

 explanatory of geological problems, ^vhich are afforded by the 

 theory of an expansive subterranean Crystalline mass preserved 

 by external pressure in a more or less solid condition beneath 

 the crust of the globe, but always ready to expand and perhaps 

 to intumesce upwards on any relaxation occurring in the over- 

 lying pressure. But I suggest it now, as I did thirty years since, 

 as the solution most reconcilable with the known facts of the 

 structure and relative position of the great elevated rock forma- 

 tions of the globe, and as a theory founded, not upon mere 

 guess-work, but on careful and extended observation of the phe- 

 nomena of both active and extinct volcanos, and the disposition 

 of volcanic products of all ages. 



Art. XVII. — On the occurrence of Natro-horo-calcite tvith Glauher- 

 Salt in the Gypsum of Nova Scotia; by Henry Haw, Professor 

 of Chem. and Nat. Hist. King's Coll., Windsor, Nova Scotia. 



The Natro-boro-calcite, to which the following communication 

 chiefly refers, must be ranked among the least common of min- 

 erals, inasmuch as it has hitherto been found in but one locality, 

 and is not yet fully described in the manuals of mineralogy. 

 The circumstances under which I have lately met with it will 

 add not a little, I think, to the interest it already possesses, as it 

 has been obtained in a new geological position, and in a state of 

 greater purity than the specimens as yet examined seem to have 

 had, so that I have been enabled to make out its true constitu- 

 tion which I belieye, for reasons presently to be mentioned, has 

 not till now been arrived at 



The brief history of the mineral is this. It was originally 

 sent, a few years since, to Dr. Hayes of Boston, U. S., from Tara- ^ 



