8 



TOPOGRAPHY OP THE 



cliff, and lets the upper part fall by its own weight. It may then wash away theruh- 

 bish formed l^y the fall and continue its attack on the cliff. Such undermining may 

 be seen in progress a quarter of a mile below the Burra Kutta Oil Springs, where the 

 brook has formed at the bottom of the cliff a low cavern not yet deep enough to make 

 the rocks above fall down. A stream that falls over a l)ed of I'ock will often, as is 

 well known, undermine it especially if there be a softer layer of rock at the bottom 

 of the fldl. The undermined edge of the fall at length comes down, the rubbish is 

 washed away, the undermining goes on again, and so a gorge is gradually formed 

 below the fall. A gorge or })air of cliffs facing each other is, then, a mark of river 

 action ; and this is generally combined with the action of rain. Such a gorge is to 

 be seen still forming on a small scale at the Chhota Ivutta Oil Springs and a few 

 hundred yards above them, although the greater part of the worl^ was done long ago. 

 Gorges formed in the same way are to be seen at JSTursingjnihar and elsewhere along 

 the southern face of the Salt Kange ; they have apjjarently been made by much larger 

 streams than now flow thi'ough them. 



The Salt Range has in the western arm of its \ee, near its point, at the village of 

 ummul, a right angled bay in its southwestern face ; and it looks as if this had 

 once been the outlet of all the waters north of the range, and as if there had been an 

 enormous ]N^iagara here that had begun to cut a gorge below for itself, before the 

 present gorge of the Indus at Ivalabagh was cut. Perhaps the great amount of salt 

 in the thick layers in the mountain near Ivalabagh by its readily dissolving and pos- 

 sibly letting the rocks above become undermined, hastened the comjjletion of the 

 gorge and gave it the start of the one at Nummul. 



c. The wearing action of the sea is almost wholly by undermining the headland of 

 a coast. The waves dash against the shore and wear it into a cliff, undermine the cliff, 

 the tidal currents can-y off the rubbish that falls, the undermining goes on again, and 

 the sea at last cuts the land down to its own level. But in l)ays the foi'ce 

 of the waA'es is lessened, the water is quieter, tlie earthy mattei's in the Avatei- 

 drop more readily to the bottom, the rivers bring in such matter from the valley at 

 the head of the bay, and this becomes silted up. A single kmg cliff or line of cliffs 

 looking down on a wide plain is then, the mark of sea cutting, llie southern escarj)- 

 ment of the Salt Range, so abrupt and striking, gives the impression of a coast line 

 formed by the sea ; and i-eally seems to have been so formed when the low land to 

 the south was under w^ater either salt or fresh, though ]X'rlia]js a little rounded by the 

 rains since then. 



(I. The frost, as everybody knows, acts by freezing the Avater in the small ci'acks 

 or pores of the rock, and so by expansion loosening ])artick\'-! oi- masses of rock or 



