BY C. HEDLKV. 319 



iiicludiiii,' O710 or more series of laminoe, as "layers." Between 

 tliese layers, there is often a bed of shale. This shale may be 

 yards in thickness, reduced to a thin sheet or spattered about in 

 discs and pebbles. 



Near Sydney, the lip of the basin bearing the brunt of the 

 pressure, the shale is rarely undisturbed. Frequently, it rests on 

 a floor which curves abruptly up and down, and underlies a roof 

 which, in a short space, makes equally sudden contortions (Plate 

 xxvi.). From its nature, the shale, deposited horizontallv in 

 calmest pools, could not have formed on such a floor or under 

 such a roof. Into present positions the shale has slid over a 

 strange floor, and been wedged under a misfit roof. Sometimes 

 a shale bed thinning out is continued by a stream of biscuit- 

 shaped flakes. These are morsels chewed in the jaws of the 

 sandstone layers. Fish-remains are abundant in some shale- 

 beds, and such are usually distorted by a very slow oblique pres-^ 

 sure they have undergone. The sudden bumping of stranded 

 icebergs could not account for the screwing these fcjssils have 

 received. Besides, under floating ice the shale would disintegrate 

 rather than bend or break. Pressure, too, is perhaps expressed 

 by the readiness of exposed shale to crumble away, due to the 

 breaking of its grain. 



The butter would ooze out, if pressure were put upon a pile of 

 slices of bread and butter. So where hard sandstone and soft 

 shale were squeezed together, the shale first gave way, and thus 

 furnishes the most obvious evidence of displacement. To some 

 extent, the false bedding disguised dislocation, but, though less 

 apparent, the sandstone exhibits its own signs of disturbance. 

 Continually it falls in belly-sags, and rises in back-humps, the 

 imprint of thrust-movements. Layers are rolled over or telescoped 

 into each other, and in places the sandstone is curled like 

 carpenter's shavings (Plate xxvii.). 



Such phenomena are well known. Mr. C. S. Wilkinson* 

 described disturbed beds at Fort Macquarie, Woolloomooloo, and 

 Flagstaff Hill, where there were "angular boulders of the shale 



* Wilkinson, Journ. Roy. 8oc. N.S.VV., xiii., 1879(1880), p. 106. 



