Pavid Milne, Esq., on FoUshed and Striated Rocks. 163 



of these blocks, about a ton in weight probably, is partly imbedded in 

 it, and the horizontal layers of sand are to be seen encircling the 

 lower half of it. It is important to observe, that this fragment is 

 rounded and smoothed at its west end, but is rough and angular on 

 (ill the other parts exposed. The gravel and travelled blocks which 

 Ih'.ve been apparently brought and laid down simultaneously with the 

 fiand, consist chiefly of greenstones, basalts, and hard sandstones, of 

 a white and grey colour. These are of the same character as the 

 rocks which occur in Salisbury Crags. But there are other houl- 

 ders in this sandy deposit, which cannot be identified with any rocks 

 in the neighbourhood. Those are, rounded blocks of red compact 

 felspar, a red sienitic porphyry, marine limestone full of encrinites, 

 and ball or clay ironstone. The depth of this sandy deposit is un- 

 known, as the new road does not reach to the bottom of it ; — what 

 is seen is from 4 to 6 feet thick. 



The other deposit of a similar character is immediately above 

 Windygowl. It consists of coarse gravel, indistinctly stratified, and 

 forming a bed about four feet in thickness, which slopes to the SE., 

 at an angle of about 30°. It so happens that the rocks, over which 

 they lie, are red sandstone strata, and that they dip the same way, 

 and at the same angle. It has been accordingly suggested, that this 

 bed of gravel was deposited before these strata were tilted up, and 

 that they acquired their dip by the elevation of the strata. But the 

 more probable explanation is, that the surface on which they were 

 thrown down, had previously a dip to the SE. The gravel consists 

 of rounded pieces of grey wacke, porphyry, compact felspar, and sand- 

 stone. 



2. The next point of a collateral nature deserving attention, is 

 the occurrence of an immense number of coarse greenstone boulders 

 to the east of Wyndygowl. Those spread over the surface of the hill 

 are well described by Mr Maclaren. Many more have lately been ex- 

 cavated, both in the operations for forming the Victoria Road, and in 

 those of the North British Railway Conq)any, near Parsons Green. 



I may take the opportunity of here mentioning, that many of the 

 large boulders exposed in the cuttings of the North British Railway 

 present polishing and strise precisely similar to the appearances at 

 Sampson's Ribs. I lately examined four or five large boulders im- 

 bedded in the stiff blue clay before referred to, at Easter Dudding- 

 ston, the upper surfaces of which were flat and very smooth, and pre- 

 sented strong marks of rubbing. On these surfaces there were 

 scratches, and in some cases ruts, which almost invariably run in di- 

 rections by compass, varying from NW. to WNW. Two of these 

 blocks were old red sandstone conglomerate, one of them old por- 

 phyry, and a third a black basalt ; all being rocks which do not oc- 

 cur in the neighbourhood, but most of which exist in Stirlingshire. 



At the sea-shore between Joppa and Magdalene Bridge, the 

 boulder clay is well exposed, and numbers of fragments of these old 



