Vol. 55-] 



NEAE MEL:vrERBY (cFMBEELAND). 



13 



movements in tlie rocks, and similar evidence is furnished by the 

 study of the general structure of the district. The exposure is close 

 to the great fault which extends in a north-easterly and south- 

 westerly direction, and brings the Melmerby Scar Limestone down 

 from Melmerby High Scar to Melmerby Low Scar, and minor faults 

 are associated with this. 



It is quite clear that most of the groovings on the pebbles and 

 on the surface of the sandstone alike are of the nature of 

 slickenside-striae, but it is of course possible that the shape of the 

 pebbles is due to glacial action, and that any glacial striae which 

 may have occurred have been obliterated as the result of earth- 

 movements. The great amount of indentation which the pebbles 

 have undergone, and the manner in which the surfaces of some 

 appear to have been squeezed off in a way which can be imitated 

 with partially-hardened putty, suggest, hoivever, that the angularity 

 of the pebbles may also be partially or wholly due to earth-move- 

 ment occurring after their inclusion in the conglomerates. 



Diagrammatic Section near Melmerhy. 



^ <^ c^ ^ ^ 



1 == Coarse conglomerate (top not seen). 



2 = Thin clayey parting, with flaky struc- 



ture, 1 inch thick, resting on the 

 striated and polished surface of 

 No. 4. 



3 = Laminated sandstone. 



4 =■ Sandstone with occasional small 



pebbles. 



5 = Crushed pebbly rock. 

 F= Fault (not afl'ecting 4 ?). 



I need hardly say that I have not described this section with any 

 desire to throw doubt upon recorded instances of glaciated pebbles 

 occurring in ancient deposits, but rather to furnish geologists with 

 a typical case of production of strise by earth-movements on a rock- 

 surface, and also on the surfaces of pebbles, which may be used to 

 contrast with the glaciated deposits. I searched for some time for a 

 single pebble which might lead the discoverer to suppose that he 

 was dealing with a glaciated stone rather than a slickensided one, 

 but could not find one that was likely to mislead anyone conversant 

 with the results of glacial action. This might perhaps be done in the 

 case of a deposit in which the pebbles were less fitted to receive and 

 retain extremely fine markings, but the variety of rocks represented 

 among the pebbles of the Melmerby conglomerate renders it 

 doubtful, though I was unable to discover any limestone-pebbles in 

 the accumulation. 



In conclusion, I may state that the specimens exhibited to the 

 Society will be placed in the Woodwardian Museum. 



