GEOLOGY OF THE EAST LOTHIAN COAST. 27 



lines represent the hypothetical extension of the igneous mass 

 and sandstones previous to the denudation which they have 

 suffered from the action of the waves. 



Professor Geikie, in his admirable treatise on the Geology of 

 the county 1 , adopts a view on this subject which is somewhat 

 different from that which is suggested in this paper. He con- 

 siders that the whole mass is an intrusive neck of rock with 

 perpendicular sides; and that it once filled up an orifice through 

 the surrounding sedimentary strata, of which it is now the only 

 remnant. 



LEVEL OF 



SHORE 



FIG. 2 



FIG. i. VERTICAL SECTION THROUGH CC. DIAGRAM (Fio. i). 



A. Orifice by which the lava ascended. B. Sandstone Beds. B'. Hypothetical 

 extension of ditto. C. Sheet of lava spread over the sandstones /?. C. Hypo- 

 thetical extension of ditto. 



He admits that the inclination of the sandstone beds towards 

 the igneous mass in the centre is a phenomenon that is some- 

 what difficult to explain, and suggests that a subsequent contrac- 

 tion of the column may have tended to produce such a result. 

 To use his own words: "In the case of a solid column of felstone 

 or basalt, the contraction of the melted mass on cooling may 

 have had some effect in dragging down the sides of the orifice 2 ." 



But, apart from other objections, it is scarcely conceivable 

 that this result should have been produced by the contraction of 

 the column. 



In his recent edition of Jukes's Manual of Geology (p. 269), 

 in which he also refers to this instance, he states that in other 

 cases of "necks" it is found to be an almost invariable rule, "that 



1 Memoirs of Geological Survey of Scotland, sheet 33, pp. 40, 41. 



2 Note on p. 41 of Mem. Geol. Survey of East Lothian. 



