156 



Note on a tank Section at Sealdah. 



[No. 2, 



where beneath Calcutta, and also on the Howrah side of the river * 

 although its depth is not everywhere uniform. Thus it is exposed in 

 the bed of the river below Garden Reach, (at very low tides,) and also 

 in the river bank at the Botanic Gardens. At these places its absolute 

 depth is about 6 feet less than at Sealdah. In three borings in Fort 

 William, on the other hand, it was met with at a depth of 51 feet 

 which, allowing for a difference of 3 feet between the actual surface 

 levels of the Fort and Sealdah, would indicate a level 28 feet lower 

 than that at Sealdah, and not less than 34 feet lower than at the 

 Botanic Gardens. The correspondence of this part of the two sections 

 is however such, that notwithstanding this great difference in level I 

 cannot but think that the bed is either continuous or approximately so. 



The peat bed rests upon a thick deposit of clay, e, sandy in the upper 

 part, but passing downwards into a stiff blue clunch, which contains 

 the stools of Sundri trees in situ at various levels, at least as far 

 down as 30 feet from the surface, or 10 feet below the peat, Two very 

 perfect specimens of these projected from the bottom of the tank at 

 the time of my visit. Their roots penetrated the clay beneath, and 

 I saw in the sides of a little well which had been sunk 4 feet lower, 

 that the clay beneath was pierced in every direction by the roots of 

 similar trees. These trees must therefore have grown at a level 

 actually 15^ feet below the lowest water level of the canal, and 13 

 feet below that of the Hoogly. 



No deeper excavation was open at the time of my visit, but I was 

 informed by Mr. Leonard, that a deeper well sunk in the bed of the 

 tank and subsequently filled up, had shewn that the clay bed extended 

 to a depth of 15 feet below the tank bottom, and rested on a stratum 

 of very loose black sand, fetid from the amount of vegetable matter 

 which it contained. According to this, the total thickness of the bed 

 is 25 feet below the peat, which corresponds very closely to that of 

 the fort section, where the peat bed rests upon blue clay with wood 

 and kunkur, and yellow clay, of a total thickness of 21 to 24 feet ; 

 and this on a stratum of wet reddish sand. 



The point of chief interest in the Sealdah section is the occurrence 

 of tree stumps in situ at the depth of 30 feet, and the evidence 



* I am informed by Dr. Anderson, that the natives have a tradition tc > the 

 effect that the Hooghly formerly passed from Cossipore some miles to the West 

 of Howrah, its present course being that of an old native canal, into which the 

 river burst its way about 150 years since, deserting its old channel. Thus tne 

 beds on the two banks of the actual river were formerly continuous. 



■fik 



