500 D. Balsillie — The Geology of Kinkell Ness. 



however, the intervening thickness of sediments is certainly a good 

 deal less than this. 



The strata that form the northern walls of the vent have, as has 

 been pointed out by Sir A. Geikie, 1 been "violently disrupted". 

 Enormous masses and blocks of sandstone and sandy shale are here to 

 be seen standing at all angles in a matrix made up in the main of 

 non-volcanic detritus, though containing abundant pieces of white 

 trap, which has inserted itself into cracks and fissures in the 

 sedimentary fragments, behaving, in fact, as if it were an intruded 

 igneous rock. These curious fragmental rocks, exhibiting always the 

 same general characters, are to be seen over and over again along the 

 Fife shores. They were probably at one time liquid volcanic mucls, 

 their present mode of occurrence being merely an expression of a 

 former high degree of mobility. 



To the student of volcanic geology these peripheral non-volcanic 

 areas in the larger vents afford considerable interest. It is obvious 

 they must have lain permanently clear of the actively erupting 

 channel; otherwise they could not have been preserved. There is 

 thus the implication that the actual shape of the volcanic chimnev 

 towards the earth's surface is that of an expanding cone ; in other 

 words, that in vertical section it would resemble in some degree that 

 of a filter-funnel held the proper way up. There is, however, the 

 alternative explanation, and one that seems very likely, that 

 sometimes they may not have been formed early in the history of 

 the vent at all but rather towards its close, when the upstanding- 

 sedimentary walls were undergoing disintegration and were sending 

 down their debris into the ash around the margins of the neck. 



The major portion of the opening is occupied by a dark tuff made 

 up of lapilli and nut-like fragments of basic lava and fine ash. In 

 this ground-mass, which is sometimes almost black from the amount 

 of intermingled coal-dust, are distributed numerous blocks of basalt 

 and of various sedimentary rocks. Conspicuous among the latter are 

 rounded or subangular fragments of a grey limestone weathering white. 

 A curious interest attaches to these. Some years ago it was found by 

 careful examination that they contain the remains of forms of marine 

 life such as Lithostrotion junceum and L. irregulare, as well as other 

 corals, brachiopods, and lamellibranchs, the species being common 

 forms in the Carboniferous Limestone Series. 2 The significance of this 

 will be appreciated when it is recalled that the strata now surrounding 

 the opening belong to an inferior group of sediments, namely, the 

 Calciferous Sandstone Series. The interpretation to be placed on the 

 observed facts would appear to be that some, at least, of the basement 

 beds of the Carboniferous Limestone Series formerly overspread this 

 portion of the county and were actually penetrated by the vent. The 

 disrupted fragments became enclosed in the agglomerate which 

 subsequently subsided within the orifice, -while the overlying and 

 surrounding sedimentary rocks have been entirely swept away. 

 Support for this opinion is obtained from the fact that wedged in 



1 The Geology of Eastern Fife, p. 208. 

 2 Geol. Mag., 1911. • 



