270 On the Strata of the Dddb Alluvium, [May, 



attaches to its circumference every substance hard enough to make a 

 sufficiently deep impression to secure its hold ; this continues until 

 every portion of the outer surface is covered, when, of course, the 

 accumulation ceases; in this state it is washed from the ravine into the 

 bed of the river, on reaching which, it is carried forward in a new 

 direction of the current of the river, which deposits it in the nearest 

 hollow in its bed, where after lying a sufficient time, the body disunites ; 

 the lighter earthy particles are swept away by the stream, whilst the 

 clay kankar, and other substances which may have been brought down 

 with them, remain as deposited therp : thus are all the necessary ingre- 

 dients at once provided for the formation of a conglomerate rock 

 except the sand, which in the course of a few hours generally proves 

 the most abundant article of the composition, when only a sufficient 

 time for the cement to set is necessary to present a rock, which the 

 carbonate of lime (which fills all interstices that may be left) ultimate- 

 ly renders the hardest, and from their situation, very frequently the 

 most dangerous rocks of the Jumna. (Specs. 6.) 



The conglomerate in which carbonate of lime is the consolidating 

 medium is generally produced by the breaking up of the beds of no- 

 dule kankar, by the supporting pillar of clay (its substratum) being 

 washed away, or other causes, the loose or interior nodules, of which 

 are then deposited in the nearest hollow lower down the stream that 

 can detain them, when from the absence of clay (excepting this dis- 

 lodgement occurs in the monsoon), the cement cannot be produced, and 

 the deposit remains until by the usual process of tufa formation, the 

 whole becomes one consolidated mass, (spec. 8,) this, however, must 

 be the work of time, during which, sand often fills many of the inter- 

 stices, and becomes a part of the conglomerate body. 



The fractured edges of remains of nodule kankar beds often present 

 this formation, although from the difficulties it has to encounter, a 

 very small proportion of the conglomerate rocks of the Jumna belong 

 to this class. The principal tufa formation that I am acquainted with, 

 was removed by Lieut. Martin, Engineers, from near the village of 

 Orowal, where the accompanying specimens were collected. (Spec. 8.) 



Most of the specimens in your hands, Sir, will speak for them- 

 selves. I select, however, one instance of the cement formation, in 

 which the fossil remains of an elephant are imbedded, which I con- 

 sider, claims a particular description. 



The site of the mass containing these interesting remains on the 

 right bank of the river, about 12 miles from Korah Jehanabad on 

 the high road to Cawnpur, directly under the village of Pachkowrie, 

 which stands nearly 80 feet above it, lying amongst an immense as- 



