ill GEOGNOSY" OF EAST LOTHIAN. 



places, columnar, and forms cliffs of considerable 

 magnitude * 



But we naturally inquire, What are the relations 

 of the rocks of this hill to those of the surrounding 

 and lower country ? In no place did we observe any 

 junction of the trap rocks of the Law with the sur- 

 rounding sandstone; nor was sandstone visible in 

 any part of the body of the hill. This being the 

 case, we must rest satisfied, at present, with what 

 may appear as the most plausible conjecture in re- 

 gard to its geognostic situation. The sandstone 

 strata, if not altered in their direction, would ;un 

 under the hill, and appear again emerging from the 

 opposite side, and thus the rocks of the Law would 

 rest over them, in an overlying position. But we 

 are not always to infer an overlying position from 

 the circumstance of the strata appearing to shoot 

 under, and emerging on the opposite side of the 

 hill ; because the mass of the hill may be a great 

 mass contained in the strata. Is it probable that 

 North Berwick Law is such a mass ? At a former 

 meeting, I described a considerable cotemporaneous 

 mass of trap, which occurs in the red sandstone 



* This, and other similar porphyries, it is probable, may one 

 day become of great importance, in an economical point of 

 view, as it contains about 9 per cent, of mineral alkali or na- 

 tron. Should a cheap mode be discovered of separating the alkali 

 from the other constituents of the rock, this hill alone would 

 afford alkali sufficient to supply Great Britain for a long series 

 of years. 



