NORTH BERWICK. 



239 



in concentric laminae, like basalt, and in apparent 

 fragments. Fig* 5. PL xiL represents several of 

 these varieties of structure. In the same stratum 

 of sandstone, one part will be red, and very com- 

 pact ; and another grey, and rather loose in its 

 texture ; and the two varieties, at their lines of 

 junction, present differences in form. These re^ 

 semble the appearances that frequently occur at the 

 junction of granite and gneiss, and are probably 

 to be explained on the same principle, viz. that of 

 cotemporaneous formation. Fig. 7. PL xii. repre- 

 sents a bed of compact red sandstone contained in 

 another of a grey colour ; and, at same time, shews 

 the waved line of junction of the two rocks. 



But we have not yet described all the different 

 kinds of structure exhibited by the strata of sand- 

 stone in this district, In some places, the sandstone, 

 within a short space, exhibits so great a variety in 

 dip and direction, that we are puzzled whether to 

 ascribe the appearances to changes induced in the 

 strata after their formation, or to refer them to 

 original formation. These perplexities, however, 

 vanish, if we view these different dips and direc- 

 tions, not as belonging to different strata, but as 

 the structure of a stratum, or set of rocks, composed 

 of distinct concretions. Fig. 3. 4. and 5. PL xii. 

 represent several of these structures. 



Many slips are to be observed in these strata, and 

 these vary from a few inches to some yards. It is 

 worthy of remark, that these changes occur in the 



