investigating the truth and applicability of the opinion of this eminent geologist.
Between Varese and Tresa is seen the section presented below. In this section the main facts commonly
| 1. Gneiss. | 2. Mica schist. | 3. Granite. | 5. Melaphyre. |
| 6. Tuff. | 8. Sand and gravel. | 9. Limestone. | 10. Dolomite. |
noticed as to the association of melaphyre with the other rocks are well typified, and it is seen that the occurrence of dolomitic limestone is not uniformly connected with the appearance of melaphyre; sometimes it adjoins granite, in other localities mica schist: it also appears that limestone is not always dolomitised in contact with melaphyre, or granite; and those geologists who have imagined that Von Buch supposed there was a real transfer of carbonate of magnesia from the augitic rock, have very naturally arrived at the inference that this district lends no countenance to the speculation. But we learn from M. Elie de Beaumont (Ann. des Sc. Nat. vol. xviii.), that this was not Von Buch's meaning, and indeed, that would easily appear from the facts quoted by him in support of his opinion. The true notion advocated by Von Buch, of these transformations of limestone, is that the eruption of melaphyre was coincident with violent disturbances and fractures of the country in a particular line parallel to the melaphyre; and that along the fissures then produced, gaseous sublimations of different kinds found their way to the surface, and altered particular rocks in their passage. The ordinary and obvious form of objection above noticed therefore fails; and it remains to be seen whether the occurrence of dolomite in definite relation to lines of melaphyre, or, to take the problem in a still more
