TREDIAN HILLS. 267 



the pebbles weathers and breaks up very mucli as au earthy trap- 

 rock mio'ht do. These older rocks are faulted on one side ag^ainst 

 tertiaiy sandstones, &c., and on the other ag'ainst low, reef-like, brecci- 

 ated masses of the nummulitic limestones bordering the plains. 

 Northwards of this faulted area the low ground is edged for a mile 

 or so by the tertiary sandstones and red or reddish cla3^s, but beyond this 

 distance the road into Mari leads through a defile, on the eastern side of 

 which are high cliffs of the same sandstones, &c. ; while on the west is 

 a narrow, broken, ridgy mass, a mile and a half in length, of the lower 

 nodular nummulitic limestone with some of the Jurassic beds. These 

 rocks are strangely smashed and wedged on their eastern side among 

 the tertiary sandstones and clays ; they are bordered by a stony low 

 bank of debris towards the plains to the west, while they abruptly ter- 

 minate to the north against the salt-hill of Mari, with the intervention 

 at either end of the line of junction of small fragmentary portions of 

 the tertiary sandstone group. 



The Mari salt-hill is an isolated mass of red rock-salt and gypseous 



marl, having an area of somewhat more than half 

 Salt-hill, Mari. ° . 



a square mile, and rising from the left (or south) 



bank of the Indus to a height estimated at between 500 and 600 (more 



nearly 540) feet. All round the hill, salt and gypsum are seen at 



intervals in the marl, the stratification of which is extremely obscure, 



but indicated here and there by certain hard flaggy or thin-bedded 



dolomitic zones with dark shaly partings, these being nearly always 



highly contorted and impossible to trace for more than a few yards. In 



the harder of these bands, cavities are sometimes seen, perhaps formerly 



occupied by cubical salt-crystals, or crystals of pyrites ; and sometimes 



the beds contain black, apparently carbonaceous, markings. These 



flaggy ^ones are generally associated with gypsum layers and sometimes 



with beds of salt, but they appear more frequently below than above the 



salt-beds. They are often several feet or in places even a few yards in 



thickness. The salt-beds vary considerably, up to 20 feet ; they are of 



the usual red or white salt, and in many exposures seemed to be earthy 



( 267 ) 



