398 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 24, 



nished aspect of these flags is referable to the same action. As a 

 negative proof in support of this opinion, it may be stated, that foot- 

 steps are rarely if ever found on the highly burnished surfaces, a 

 circumstance which may be accounted for by the friction having ob- 

 literated all trace of these markings. 



The great extent, extreme thinness, and general uniformity of the 

 alternating laminse of brown and red sandstone composing these flags, 

 indicate a wide and undisturbed tranquillity. The strata which lie 

 above the flags, however, show that this uniform tranquillity no longer 

 prevailed. The false-bedding of the strata, the alternations of fine- 

 and coarse-grained layers, as at Bankend, and their variable thick- 

 nesses, indicate the existence of local modifying influences. 



The change in the circumstances under w^hich the succeeding beds 

 were deposited, appears to have been gradual and irregular, both from 

 the mode in which the conglomerate occurs at Netherwood quarry 

 (see fig. 2), and also from the interpolated beds of variable sandstone 

 which are met with in the lower portion of the Mid Craig. 



The contour of the country surrounding the sandstone on every 

 side, except the south, is such as to show that at the period when this 

 formation was being deposited, the hills of whin on the east, north, 

 and north-east, syenite and granite on the west and south-w^est, formed 

 the boundary of a bay into which the waters of the ocean flowed. 

 By the force of the breakers against these rocks immense quantities 

 of angular fragments were detached, and afterwards in part carried 

 towards the entrance of the bay by the reflux action of the tide. The 

 afflux of the tide probably transported from the south the larger por- 

 tion of the sandy matrix of the conglomerate. The sand was pro- 

 bably derived from the coal beds of West Cumberland with their nu- 

 merous deposits of grit, which must have been exposed at the time 

 of the deposition of the new red sandstone. The local diff'erences 

 also in the composition of the conglomerate bear evidence to the 

 manner of its formation. 



At Cleuden Mills we meet with no traces of either syenite or gra- 

 nite, which would have been present had any current prevailed from 

 the south, xlt the Craigs we meet with them only in small quanti- 

 ties when compared with the conglomerate on the south-west of Caer- 

 laverock. At this latter locality the neighbouring mountain of CrifFel, 

 which is situated about three miles westward, has furnished an abun- 

 dance of materials for the formation of this deposit. The fragments, 

 therefore, which form the Caerlaverock conglomerate, have not come 

 from the same direction as those which constitute this deposit at the 

 Craigs or Cleuden Mills, i. e. from the north, but from the west. 

 The base of Criff'el, presenting a bold granitic barrier, against which 

 the force of the water exerted itself, supphed a debris which gradually 

 formed a sloping sea-bottom eastward ; hence the reflux action of the 

 tide in this locality would be eastward, transportmg material in that 

 direction to form the conglomerate of Caerlaverock. 



Both the upper and the low^er portions of the conglomerate indi- 

 cate by the occurrence of sandstones that the change of conditions 

 was gradual ; and in the isolated fragments of rock which are met 



