IN THE FAROE ISLANDS. 219 



The first example we had an opportunity of examining, of 

 that species of tuffa, immense beds of which form so remark- 

 able a feature of Iceland, was observed forming part of a very 

 curious rock on the west coast of the island of Vaagoe, call- 

 ed Tindholm. We saw the same sort of tufFa in different 

 places ; particularly at the bottom of the promontory called 

 Niepen, in Stromoe. It may also be seen on the beach, near 

 the village, in Naalsoe. 



E e 2 The 



From the basis or the included masses. As it is not in any case easy, I 

 may say possible, to determine to what specific substance we ought to refer 

 the basis, which varies in several respects, it may perhaps be best, when there 

 is any uncertainty, to describe both it and the included masses ; for pro- 

 lixity is, in every description, preferable to want of perspicuity. Trap-tuff im- 

 plies, either that the basis is derived from Trap, or that the included masses are 

 Trap, or that both have the same origin. Now, as the rock in question often 

 contains sandstone, and sometimes wood ; and as in Iceland and other volcanic 

 countries, it contains lava and other volcanic substances ; the term Trap-tufF 

 conveys none of these important particulars. Correctness seems, therefore, to 

 demand some reform. I would propose that the basis should be understood ge- 

 nerally, as Professor Jameson has described it, to be " rather a loose, spongy, 

 " clayey basis," 11 and that we should relinquish the term trap, and use, as a ge- 

 neral term, the word tuff, or the original and more harmonious Italian Tuffa, and 

 describe the included masses. Thus, in Iceland, I met with tufFa, the compo- 

 nent parts of which were so minute, that it resembled red sandstone ; tuffa inclu- 

 ding rounded masses of trap, from a size very minute, to many feet in thickness ; 

 tuffa including masses of trap, lava, slags, and mineralized wood. Here the de- 

 scription appears to be absolutely necessary to prevent misapprehension ; and in- 

 stead of being at all offensive, it affords perfect satisfaction : whereas, were I to 

 use for them all merely Trap-tuff, many important particulars would be omit- 

 ted. 



Objections also arise to the term Calc-tuff, which may be understood to mean 

 a calcareous basis, cementing together substances, the nature of which we are left 

 to imagine. The included masses being sometimes entirely calcareous, and 

 sometimes heterogeneous, the term, by itself, conveys nothing satisfactory. For 

 fragments connected by a solid basis, the old term breccia seems to be unob- 

 jectionable, when qualified, as circumstances may require, by a description of 

 the basis and the included masses. 





