158 PROCEEDINGS or THE GEOLOGICAL SOCIETY. 



MonaDs. All over the inland tract the necks form more or less 

 marked eminences, rising frequently into conical hills, such as Kelly- 

 Law and Largo Law, which are conspicuous landmarks from the 

 southern side of the Pirth. But the distinguishing characteristic of 

 the area is the display of the necks along the coast and the manner 

 in which their form, composition, internal structure, and relations to 

 the surrounding rocks have there heen laid open. No such series 

 of dissected vents is to be met with in the volcanic records of any 

 other geological period within the compass of these islands. 



Having already given some account of the chief characters of 

 these necks in the east of Fife, I need not on the present occasion, 

 do more than refer to my published paper for details.^ The materials 

 that have filled the vents are agglomerates and tuffs, not infrequently 

 with intrusions or plugs of basic lavas. There does not appear to 

 be any relation between the diameter of a funnel and the size of 

 the blocks that now fill it. At the Buddo Ness, for example, on 

 the coast east of St. Andrew's, we find a little neck not more than 

 60 feet in diameter, yet packed with blocks of shale 6 feet long, 

 while the sandstone through which the orifice has been drilled is 

 altered into a kind of quartzite for several yards away from the 

 edge. On the other hand, some of the larger necks consist of com- 

 paratively fine tuff. 



On the shore, where denudation has been most eff'ective, there 

 exist only the necks and their associated dykes and veins. In 

 the interior, however, at the large necks of Largo, there still 

 remains a good deal of the fragmental matter that gathered around 

 the vents from which it was discharged. There must be an area 

 there of not much less than four square miles covered with tuff. Un- 

 fortunately the sections are not numerous, and it is hardly possible 

 to map out separately the tuff which forms-the vents from that which 

 is lying on the Carboniferous rocks around them. There are probably 

 at least three necks in this area of tuff, that is, there were here three 

 volcauic vents, probably opened successively, and almost touching 

 each other, like groups of puys in Auvergne. On the outskirts of 

 the area of tuff it is possible to see the junction of the volcanic 

 detritus with the Carboniferous Limestone series underneath, and 

 to ascertain that there is a strong unconformability between them. 

 This relation goes to confirm the inference as to the great interval 

 of time between the eruptions of these volcanoes and the deposition 

 of the rocks of the Carboniferous period. 



1 Trans. Eoy. Soc. Edin. vol. xxix. (1879) pp. 455-474. 



