87 



hills, occuriug in fissures of tlie rock-beds, as veins in stones, 

 (formed probably in cracks,) in the interior of fossil shells, and in 

 other situations which have afforded space for the crystals to 

 form. These crystals are seldom transparent, being generally 

 tinged in colour by iron or other impurities. 



This subject leads to some considerations of interest regarding 

 the abstraction of Lime from the existing strata of our hills. 

 It would require much accurate observation of the chemical 

 character of the various streams which flow from the Cotteswold 

 Hills, and careful gauging of the volume of their waters, to 

 ascertain even approximately the total weight and bulk of Lime 

 annually abstracted. The portion re-deposited as Tufa is infini- 

 tesimal compared with that which is borne to the ocean in an 

 invisible combination with the waters of the Severn, the Avon 

 and the Thames. From experiment, it appears that even the 

 Broadwell stream at Dursley carries away at least eighty tons 

 per annum, and this shows how great the total quantity must 

 be. Year by year this loss is scarcely perceptible ; but in the 

 review of past geologic periods may we not see here an agent 

 by which, in connection with others, vast ancient deposits have 

 been disintegrated and conveyed for re-disposition in the beds 

 of ancient oceans ? In this manner may not the lime which 

 forms so large a portion of the Lias of our vale and the Oolites 

 of our hills have been abstracted from pre-existing lands, 

 where situate we, as yet, know not^ and have been invisibly 

 conveyed by streams, rivers, and ocean currents, and then 

 through the high temperature of the existing waters have 

 been disengaged and deposited on the floors of those ancient 

 oceans — in the case of the Lias in a calm still ocean, whilst 

 in the case of the Oolitic ocean, the waters were probably in 

 a sufficiently disturbed condition to hold in suspension minute 

 organic and inorganic particles, to which the Lime, when set 

 fi'ee, attached itself, forming the roe-like grains which give 

 to the Oolites their peculiar character. The rivers which 

 thus bore their invisible freight of lime also carried other 

 inorganic atoms, as well as occasionally organic remains from 

 the distant lands, with pebbles of various old formations, the 



