Manchester Memoirs, Vol. Ixii. (1918), No. 9. 5 



action of the wind has not been sufficient to produce anything like 

 the beautifully sharp edges and faces seen in the fractured examples. 



Though most of the stones have been split on one face only, 

 usually along a joint or bedding plane in the case of the sedi- 

 mentary rocks, there are others which have been split in various 

 directions, and modification of these faces by sand-blast has resulted 

 in the production of three- or even four-edged facetted pebbles. 



The occurrence of these numerous modified split pebbles at 

 Pendleton is interesting in point of view of the fact that similar 

 examples have been recorded from various other localities both in 

 Europe and in America. 



The majority of the Pendleton facetted stones show a rounded 

 water-worn base ; but others, including the large example mentioned 

 previously, still retain very definite traces of Glacial striae on their 

 bases. 



Several pebbles occurred in the sand completely inverted, and 

 some show distinct traces of erosion on both sides — that is, they in- 

 dicate wind action for a time with one side up, followed by similar 

 action after the pebble had rolled over. 



A number of the stones were orientated in situ, and in some 

 of these the eroded fractured surface faced north-westwards, in 

 others westwards, and in others again south-westwards — the direc- 

 tions of the present prevailing winds. But as these also show wind 

 erosion on other parts, it does not definitely indicate that these were 

 the particular winds which eroded them. 



Differentiation, according to varying hardness and composi- 

 tion, is well displayed on the granites, porphyries, grits, etc., where 

 the weaker constituents have been strongly eroded, leaving the stones 

 with an irregularly pitted surface, in some cases over the whole upper 

 surface of the pebble. On the volcanic ashes, inequalities in texture, 

 imperceptible to the naked eye, have been searched out, with the 

 result.that the pebbles have a roughened surface consisting of minute 

 pimples of harder material standing out in relief. 



The facets are not absolutely plane surfaces ; they are usually 

 somewhat concave, grooved, or fluted. The concavity may be in 

 part original and owing to conchoidal fracture. The facets are 

 variable in number : the majority of the. stones present one face 

 only — a modified split face ; others two or more. Some examples 

 with flat tops show three, four, or even five incipient facets. On 

 some stones, chiefly igneous, the grooving is of the nature of parallel 

 series of elongated pits running transversely across the face and not 

 at right angles to the edge (see Fig. 14). "On such stones as these 

 the facet angles are very irregular ; but on the quartzites and fine 

 volcanic ashes the edges are much straighter and sharper. A fair 

 proportion of the stones are elongate-oval and these usually possess 

 a long median ridge, with occasionally two small ridges diverging 

 from it at one end. Several small flat oblong pebbles, especially of 

 quartzite, are interesting from the fact that they must originally 

 have had fairly vertical sides ; these have been worn by blown sand, 

 leaving the stones with two almost vertical sides and two somewhat 



