of east Lothian. 



47? 



CALC-SPAR. 



Small veins of this spar are observable in every 

 part of the formation. At North Berwick, they 

 are found a few inches wide, traversing the trap- 

 tuff. They are yellowish and reddish-white, and 

 the tendency to assume the prismatic form, gives 

 them at the edges a fibrous appearance ; and these 

 fibres are, in all the cases examined, perpendicu- 

 lar to the walls of the vein. When a great num- 

 ber of these veins are exhibited together, the prin- 

 cipal ones have always the same general direc- 

 tion. 



Owing to the covered state of the country, I 

 have not been able to satisfy myself as to the di- 

 rection, inclination and dip of veins. 



It may be worth observing, in a controversial 

 or theoretical point of view, the very unfrequent 

 occurrence of veins of these trap-rocks, or what are 

 very improperly called whin-dikes, intersecting 

 the subjacent strata of this county, one-half of 

 which is covered by trap. We should certainly 

 expect, that if this immense mass of trap, or, 

 as it is sometimes called, whin, was erupted 

 front below by an expansive effort, the regu- 

 lar strata of the country would be rent asun- 

 4er in all directions, and dikes, interjected beds, 



