244 On the Alpine Glacier, Iceberg, [No. 159. 



Furrows, striated and polished surfaces. The sides and surfaces 

 of exposed planes, bosses, boulders, erratic blocks and masses of rock in 

 situ, should be examined for polishings, striae, or furrows, more par- 

 ticularly the surfaces of rocks which are protected by a covering of soil 

 or turf, which it will be necessary to remove for this purpose. It must 

 be noted whether the striae and furrows are parallel or otherwise ; 

 whether oblique or horizontal, and their general direction. If in a 

 valley, whether they run in the same direction as the valley, and di- 

 verge from it at the outlet- 



Whether they run in right lines, with even, uniform polished sur- 

 aces, or are shallower or deeper, varying according to the different 

 degrees of hardness or softness of the different portions , and veins of 

 the rock, and whether their course is at all sinuous. " Slickensides" 

 or the polished and striated surfaces of walls of fissured rocks and vaults 

 caused by their friction in dislocation, must not be confounded with 

 the marks of general or aqueous action. 



The observer should endeavour on the spot to ascertain the possibili- 

 ty, or impossibility, by the supposition of present floods, rains, landslips, 

 or other causes now in existence, of explaining these depositions, 

 furrows, &c. ; and also of the circular, oval, and spoon-shaped cavities, 

 with smooth sides in rocks, termed rock-basins, which are often united 

 by shallow gutters. It should be ascertained whether they are or are 

 not within the reach of the highest inundations, or temporary petty cas- 

 cades caused by monsoon rains, the periodical risings and fallings of 

 rivers ; whether empty or containing sand, or pebble ; the nature of the 

 pebbles, the dimensions and shape of the cavities, and nature of the 

 surrounding ground. 



Engineers, surveyors, and other servants of Government stationed 

 in districts, will have time to note on all these desiderata as affecting 

 their particular district ; but it will be sufficient for men who travel 

 rapidly from station to station, or on the line of march, to bear 

 in mind that the great points to ascertain are— whether the blocks 

 and gravel they see are composed of the adjacent and subjacent 

 rocks or not, their distance from their native beds; to send speci- 

 mens of all : and to see that the blocks and marks on the rocks are 

 above the influence of present water-courses, inundations, and 

 rains. 



