150 B. Smith—Ball or Pillow-form Rocks. 
Other examples occurred (i) in a quarry between the road and 
river east of Coed Fron-fraith; (ii) in a quarry about 200 yards west 
of Tyddyn-main; (ili) in a quarry at l'yn-y-ffridd in ashy sandstone, 
where shales are pinched in between two balls; (iv) on Moel y 
Gwelltyn, where the balls are from 18 inches to 2 feet in thickness ; 
(v) in the crags west of, and overlooking, Moelfre (Fig. 1); (vi) in 
a quarry south of Pant-er-eos-uchaf; (vil) in numerous quarries 
and crags between Moelfre Hall and Moeliwrch on Gyrn Moelfre. 
In some cases it is possible to study sections of the ball structures 
on joint faces where the lamination has been rendered visible by 
weathering. In a quarry about 200 yards west of Tyddyn-main 
(ii above, Fig. 4) a flat broken surface of a ball, in a big lenticle of 
sandstone, reveals its internal structure, for the exposed lamine are 
curved back upon themselves in a sharp fold, to which the outer curve 
of the ball conforms. 
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ome) 
\ S the 1 
a ah z es 
—--------~-— > 
a) 
Fic. 5.—-Contorted layers in sandstone near Pentre, Llansilin. 
A better section is visible in an old quarry in a wood 200 yards 
east of Pentre, on a nearly vertical joint face which runs approxi- 
mately in the direction of the dip (Fig. 5). It shows a well-laminated 
and slightly drift-bedded sandstone, in which some of the laminze 
(about 12-15 to the inch) are strongly contorted, folded back upon 
themselves, and cut off from other parts of the rock by faults. The 
rounded ends of these curved masses are often buried in apparently 
structureless sandstone, whilst the disturbed horizon is both underlain 
and overlain by normally bedded sandstone. At some future date the 
balls will be developed by differential weathering of the structureless 
parts of the rock. 
