LOGIN KOETH-INDIAN GEOLOGICAL CHANGES. 193 



were not deposited in stUl water, but that tliey formed the beds and 

 banks of streams. If there were any doubt on this point, I think it 

 is completely set at rest by small stones and rounded clay boulders 

 having been met with at from 250 to 295 feet below the surface. 

 We see the very same in our torrents every day a few miles below 

 the hills, where these streams are rapid ; so it is only natural to con- 

 clude that these small stones and clay boulders were moved down 

 the beds of rapid torrents in the same manner as they are at the 

 present day. 



With such facts it appears to me that, so far as has yet been 

 reached, all the deposits were made by running streams along their 

 course, and that none of these strata ever formed the bottom of lakes 

 or inland seas. 



It may also be stated here that possiblj^ Central and Southern 

 India may have been an island, the rocks at Delhi forming its 

 northern extremity, the coast-line taking a south-westerly direction 

 towards Bombay and Scinde, while the north-eastern shore would 

 have followed very much the present course of the Jumna to where 

 it joins the Ganges, and then very nearly the course of the Ganges 

 to Rajmahal, which would have formed the most eastern portion of 

 the island. Be this as it may, one thing appears very certain — that 

 here at Umballa, at a very late date (speaking in a geological sense) 

 the sui'face of the ground was only half the height above the sea 

 that it is at present ; and as far as we can judge from the gradually 

 decreasing slope of the country from the hills to the sea, there has 

 been no marked disturbance (with one exception) throughout the 

 plains of Northern India, either along the valley of the Indus or 

 that of the Ganges, but all the depressions which now exist through- 

 out this large tract are due to denudation within a very late period 

 of the world's history. This gradually decreasing slope is so 

 uniform that, if the question were more fully gone into,^I beheve it 

 would be found to approximate to a true parabola, as was first de- 

 monstrated by Mr. A. Tylor in certain cases* ; and if this be true, 

 it opens cut an important field for investigation, not only to the 

 geologist, as it would aid in determining dates, but to the hydraulic 

 engineer, as it would throw much light on the vexed question of 

 scour and deposit. Should this law be a correct one, it at once 

 shows how the slope is dependent on the load carried by flowing 

 water, and that we cannot rest contented with our empirical rules, 

 which, for all we know to the contrary, may be quite opposed to the 

 laws of nature. 



Another very interesting fact to which I would here beg to draw 

 particular attention is, that at a depth of 250 feet small stones and 

 clay boulders, which indicate great velocities, were deposited on the 

 softer soils underlying them. As these softer soils are abraded by 

 velocities of a foot or even six inches a second, how comes it that 

 these soils were not scoured away by probably ten times these velo- 

 cities ? 



The conclusion I have come to for several years back is, that 

 * See Q. J. a. S. vol. xxv. p. 72, 1869. 



