480 OLIVE EARTH. 



current was renewed, and with it were brought and deposited the 

 layers of drifted pebbles, sandy gravel first, and next sand, which 

 now overlie all the olive earth and eocene formation. This lower 

 sandy gravel is ferruginous, and everywhere supplies ferruginous 

 spring-water, and probably the impregnation being partly in the 

 form of sulphate of iron. Both the sulphates of iron and of 

 alumina are sometimes perceptible to the sight and taste, in these 

 strata. The slowly oozing spring-water thus bringing either of 

 these salts of sulphuric acid, must gradually decompose any carbo- 

 nate of lime in contact. And hence, the higher deposit of what is 

 now olive earth, being permeable by water, has had all its former 

 carbonate of lime changed to gypsum, and this, in solution, mostly 

 removed by the water passing off. If these suppositions are correct, 

 the olive earth ought still to contain all that it did formerly, when 

 it was marl, except the carbonate of lime ; and with some increase 

 of sulphate of lime. Hence, this earth ought to have more or less 

 of fertilizing value and enough to be worth using, especially as 

 its very laborious excavation and removal have always to be 

 effected, for the purpose of reaching the marl below. I>ut it was 

 universally believed that the olive earth was useless ; and it was 

 put to no use, not only by those farmers who had good marl below, 

 but by others who encountered all the labour of uncovering, and 

 removing this sticky and troublesome layer, to reach merely the 

 gypseous earth below, probably worth no more than the olive earth, 

 except for its very small proportion of carbonate of lime. While 

 I drew marl from other land to my present farm, the distance was 

 too great for me to try this olive earth as manure. But since I 

 have (very lately) discovered good marl, of workable thickness, on 

 Marlbourne farm, I have carried out all the overlying olive earth, 

 though it is more sandy here than is usually found. I had begun 

 this course before having heard of any useful effect of such appli- 

 cation. But since (in the summer of 1852), I have learned very 

 remarkable effects of other (and probably much richer) olive earth, 

 as tried by two neighbouring farmers, Messrs. Henry Jones and 

 John Beale. The most accurate and conclusive of these trials 

 (though all were very beneficial) was an application of this earth 

 alone, 400 bushels to the acre, on stiff and poor (long exhausted) 

 land. The application was made for the corn crop of 1850, and 

 produced not much, if any, perceptible effect. The benefit was 

 much greater, though still small, on the succeeding crop of wheat. 

 But of the next following clover, which I saw in May and June, 

 1852, the growth was more luxuriant than any on the richest other 

 land; and the effect of the olive earth alone, was greater on the 

 clover (as compared with adjacent ground without this or other 

 dressing) than from marl, with its unquestionable accompaniment 

 of gypsum, or other manure elsewhere on similar lands of this 



