. The Quarterly journal of the Geological Society of London. in the limestone under the basalt, rhombs of ehalybite fringe thewalls of drusy cavities and veins, the rest of the space being filled Vol. 60. IGNEOUS ROCKS AT SPRING COVE. 16: in with clear secondary calcite, Avhile limonite and haematite havebeen subsequently deposited. In some instances the limestone, more especially that occurringas irregular lumps in the tuff, is so cracked and broken, evidentlyduring the movement of the flow, as to suggest that it must have Fig. 8.—Portion of an included lump of limestone in been hard
. The Quarterly journal of the Geological Society of London. in the limestone under the basalt, rhombs of ehalybite fringe thewalls of drusy cavities and veins, the rest of the space being filled Vol. 60. IGNEOUS ROCKS AT SPRING COVE. 16: in with clear secondary calcite, Avhile limonite and haematite havebeen subsequently deposited. In some instances the limestone, more especially that occurringas irregular lumps in the tuff, is so cracked and broken, evidentlyduring the movement of the flow, as to suggest that it must have Fig. 8.—Portion of an included lump of limestone in been hard and consolidated before the extrusion of the lava, andwas probably torn from the vent and ejected with the igneousmatter. Small oval bodies, generally a few inches long, occur in the basalt:these, when broken, show a yellow or red shell of carbonate of lime, 168 mr. w. s. boulton ox the [May 1904, the rest being filled with, pure white, secondary calcite, and in somecases quartz ; indeed, in a few instances, rounded or oval bodies upto a foot in length consist entirely of silica. These may be lumpsof limestone, burnt and hardened on the outside by the hot lava*their centres being subsequently removed in solution, the hollowsthus formed serving as receptacles for secondary calcite or quartz ;while in a few cases the whole lump of limestone has been replacedby silica. It is possible, however, that some of them may be largevesicles rilled with secondary minerals. But, in most cases, the general shape and behaviour of the lime-stone-masses, particularly between the spheroids of
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectgeology, bookyear1845
