384 



ITR. G. H. MORTON ON THE CAEBONIFEEOUS [Aug. 1 898, 



visible. The debris from the old shafts consist principally of dolomite 

 containing pearlspar, calcite, cerusite, chalcopyrite, malachite, and 

 anthracite, associated with green carbonate of copper impregnating 

 the dolomite and often coating the crystals of chalcopyrite. 



There are very 

 few faults in the Fig. 1. — Plan of lodes at Great Orme's Head. 

 limestone, and 

 they seem to 

 have had little 

 influence on the 

 varying dip of the 

 strata. To any 

 one sailing round 

 the Great Orme's 

 Head the general 

 horizontality of 

 the strata is re- 

 markable, except 

 on the east, where 

 the beds are seen 

 to bend upwards 

 at an angle of 

 30°, and expose 

 the lowest in the 

 cliffs about the 

 Happy Y alley, the 

 Pier and the 

 higher portion of 

 Llandudno, and 

 Pen MorfaLodge. 

 Along the north- 

 ern cliff the beds 

 generally dip to 

 the east at angles 

 of from 5° to 10°, 

 but the inclination varies with the undulation of the strata, and the 

 rocks are often seen to dip in other directions. The constant ex- 

 posure of the limestone rendered it easy to work out the subdivisions, 

 and to show the area of each on the map of Great Orme's Head 

 (fig. 2, p. 386). Unfortunately, the actual base of the Carboniferous 

 Limestone is not exposed, and the highest beds have been denuded. 

 The following synopsis shows the subdivisions that occur and the 



probable thickness of each : — 



Feet 

 Uppee Grey LmESTONE, with 18 feet of shale at the base 200 



(Upper beds, with 20 feet of | onn^ 

 rubble and shale at. the base. J 

 r 550 

 Lower beds, with 7 feet of 

 black shale at the base. 



[Scale : 1 inch = about 175 yards. The dotted obhque 

 vein is small, and bears no copper, but has the effect 

 of a cross-course on the north -an d-south lodes.] 



250 



LowEB Brown Limestone or Dolomite 400 



1150 



