Geological magazine . TidSill Conglomerate. 115 into a roclc which has some resemblance to the bottom, rocTc. (Theitalics are not Prof. Bonneys.) In the discussion which followed, Prof. Hughes pointed out, as theresult of his own mapping of the district, that Prof. Bonney hadmisapprehended the direction of the dip, having been misled by thevery deceptive appearance of the surface of the quarry, and hadmistaken the patches of conglomerate sticking to the face of thequarry for alternating beds of conglomerate and granitoidite. Hefurther stated that the conglomerate really dipped away from TwtHil
Geological magazine . TidSill Conglomerate. 115 into a roclc which has some resemblance to the bottom, rocTc. (Theitalics are not Prof. Bonneys.) In the discussion which followed, Prof. Hughes pointed out, as theresult of his own mapping of the district, that Prof. Bonney hadmisapprehended the direction of the dip, having been misled by thevery deceptive appearance of the surface of the quarry, and hadmistaken the patches of conglomerate sticking to the face of thequarry for alternating beds of conglomerate and granitoidite. Hefurther stated that the conglomerate really dipped away from TwtHill, passed up into brown sandstones on the rim of thequarry, and was the basement bed of the Cambrian, resting uponthe Pre-Cambrian granitoid axis, as indicated in his section drawnacross the same ridge nearer Bangor (Q. J, G. S. Dec. 5th, 1877).To make the matter perfectly clear, I give a ground-plan of thequarry (Fig. 1). Prof. Bonneys section, to which the description Fig. 1. (Ground Plan of Twt Hill Quarry.). WSW a. Granitoid rock. b. Twt Hill Quartz conglomerate. c. Brown sandstone. A B. Line of Prof. Bonneys D. Line of Prof. Hughes section. above quoted applies, was taken along the line A B. The section(Fig. 2) is a copy of Prof. Bonneys, given in Q. J. G. S, vol. 321, and is a reduced representation of the diagram exhibited at Fig. 2. Prof. Bonneys section. (A to B. Ground Plan.
Size: 2285px × 1093px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookidgeologicalma, bookyear1882
