R, D. Oldham — Facetted Pebbles from the Punjab. 33 



compelled to allow that their occurrence in their present position 

 is primarily due to the action of floating-ice. So much has long been 

 allowed by all who know the bed. 



Of these blocks of stone an appreciable proportion show a flattened 

 striated surface, exactly like that produced by glacial action ; but a 

 peculiarity of this boulder bed is that a very large proportion of 

 those blocks which show this feature are not striated on a single face 

 only, but on several ; and in some cases the original form of the 

 pebble is so completely obliterated, and the facets meet on so clean- 

 cut an edge, that the pebble assumes almost the appeai-ance of a 

 crystal. Something similar to this is known in the Boulder-clay of 

 England ; instances were quoted at the British Association, and I 

 have myself seen a pebble from the Boulder-clay of the Midland 

 Counties so striated on three faces ; but these surfaces did not meet 

 in a sharp edge, like those so commonly met with in the Salt Eange 

 specimens. 



Having shown that the occurrence of these pebbles in their 

 present position is due to the action of floating-ice, we have next to 

 consider whether their peculiar form is also due to the action of 

 ice, and if so whether as coast-ice or in the form of a glacier. 



A suggestion was made at the British Association that the facetting 

 might be due to the action of wind-blown sand ; this, however, I 

 cannot admit. Without egotism I may say that I have had oppor- 

 tunities of studying the erosive action of blown sand such as fall to 

 the lot of few geologists. I have seen numbers of stones facetted by 

 the sand blown against their different faces as they were ovei'turned 

 from time to time through one cause or another ; but I have never 

 seen anything which, to a practised eye, resembled these Salt 

 Eange pebbles any more than these latter do a crystal of felspar. 



Where blown sand acts on a rock sufficiently bard or fine-grained, 

 a polished surface, marked with numerous fairly parallel scratches 

 in the direction of the prevailing wind, is produced. These scratches, 

 however, could not be confounded with glacial strias ; for they are 

 such as would result from particles of grit getting into an artificial 

 polisher, and are very different from the clean and finely-cut scratches 

 produced by glacial action. Where the rock is softer, it is often cut 

 into grooves parallel with the direction of the prevailing wind ; 

 these, too, are not like the grooving produced by ice, but broad 

 shallow channels separated by sharp-crested ridges, giving the rock 

 an appearance as if it had been roughly dressed with a carpenter's 

 gouge. In any case there is an entire absence of anything approach- 

 ing to a sharp edge except in the direction of the wind, all angles 

 oblique or transverse to that being rounded off. Now the facetted 

 pebbles and boulders of the Salt Eange show by the direction of the 

 strife on them that in almost every case the facets are due to some 

 cause acting in a direction more or less transverse to the line along 

 which they meet ; consequently the facets cannot be due to the action 

 of blown sand, which would have rounded off" any angle so situated 

 with reference to the direction in which the sand was drifted. 



The number of stones showing one or more striated surfaces pre- 



DECADB III. — TOL. IV. — NO. I. 3 



