chap. i. Calcareous Matter entangled in Lava. 1 7 



torrent, on which the lava rests, we may conclude that 

 the stream was of subaerial origin. I was unable to 

 trace it to its source, but, from its direction, it seemed 

 to have come from Signal Post Hill, distaut one mile 

 and a quarter, which, like Red Hill, has been a point 

 of eruption subsequently to the elevation of the great 

 basaltic plain. It accords with this view, that I found 

 on Signal Post Hill, a mass of earthy, calcareous matter 

 of the same nature, mingled with scoriae. I may here 

 observe that part of the calcareous matter forming the 

 horizontal sedimentary bed, especially the finer matter 

 with which the embedded fragments of rock are white- 

 washed, has probably been derived from similar volcanic 

 eruptions, as well as from triturated organic remains : 

 the underlying, ancient, crystalline rocks, also, are as- 

 sociated with much carbonate of lime, filling amygda- 

 loidal cavities, and forming irregular masses, the nature 

 of which latter I was unable to understand. 



Considering the abundance of earthy lime near the 

 summit of Red Hill, a volcanic cone 600 feet in height, 

 of subaerial growth, — considering the intimate manner 

 in which minute particles and large masses of scoriae 

 are embedded in the masses of nearly pure lime, and 

 on the other hand, the manner in which small kernels 

 and streaks of the calcareous powder- are included in 

 solid pieces of the scoriae, — considering, also, the similar 

 occurrence of lime and scoriae within a stream of lava, 

 also supposed, with good reason, to have been of modern 

 subaerial origin, and to have flowed from a hill, where 

 earthy lime also occurs : I think, considering these 

 facts, there can be no doubt that the lime has been 

 erupted, mingled with the molten lava. I am not 

 aware that any similar case has been described : it 

 appears to me an interesting one, inasmuch as most 

 geologists must have speculated on the probable 



