1 04 Dr . B E R G E R 0// />6^ physical Structure 



is of a bluish colour and a crystalline grain ; it is here also frequently 

 intersected by veins of calcareous spar. The cliffs near Stonehouse 

 being much exposed to the action of the sea, afford very distinct 

 proofs of its effect on the most tender parts of the rock. It has made 

 in several places erosions or crevices of various extent, which have 

 been afterwards filled by a gravelly sand thrown up by the sea, and 

 which has, by drying, become so coherent, that one might be led 

 into error, by conceiving that the sand alternates in beds with the 

 limestone. 



But it is at the eastern end of the Flying bridge, on the left bank 

 of the Plym, that the transition limestone is found in its true cha- 

 racter. I have no where seen it so well characterized, not even at 

 Meillerie in Savoy, on the borders of the Lake of Geneva. The 

 strata have the same direction and the same degree of inclination as 

 those at Cat water. There is a quarry belonging to Lord Borringdon, 

 which is an excellent spot for studying it. This limestone is black- 

 ish-brown, several rhomboidal plates of calcareous spar may be seen 

 disseminated through the mass, and it suddenly assumes in the same 

 stratum, all the characters of a shining slate ; the rock in this last 

 state effervesces less briskly with acids. 



On quitting the coast, and advancing into the interior of the 

 country, there is seen on the road from Saltram to Plymptom Earle 

 a slaty amygdaloid, the base of which is of a purplish-brown colour, 

 the nodules calcareous, and the greater part of them very minute. I 

 found in the same neighbourhood, on the surface of the fields, in 

 adventitious blocks and pebbles, another species of amygdaloid, the 

 base of which is greenish -grey, and has the lustre of satin ; several 

 of the nodules being completely decomposed, had left corresponding 

 empty spaces. 



I cannot say v^'hat formation is found on the shore to the east of 



