C8 FLINT FOSSILS. 



falling to pieces.* It was proposed to wash their fronts 

 with this siliceous white wash, and thus preserve them from 

 further decay. Be that as it may, it is a fact that they 

 can render the softest stone, even soft sand, as hard as 

 flint. They do, in fact, manufacture stones. There is 

 actually such a thing as liquid flint. Man makes it, 

 and nature makes it. Now, you have only to suppose 

 an irruption of liquid flint into soft strata, and very 

 soon after the rock becomes metamorphic. 



" I saw, with Mr. Peach of Wick, many of his Dur- 

 ness Silurian fossils both from the limestone and 

 quartzite. Hugh Miller knew of fossils in quartzite, 

 found to the west of Thurso, such as Worm Holm. The 

 hard metamorphic quartzite had once been loose sand, 

 and under the action of the weather had become sand 

 again. 



"Many of Mr. Peach's limestone fossils were of 

 flint. Indeed, all that I saw were flint casts. The shell 

 had decayed ; silica had gradually filled up the place of 

 the shell ; and you saw a form like it. Others were 

 interior casts. But' the limestone was not equally hard. 

 Now these were from metamorphic rocks rocks changed 

 without fire, or any heat. 



"No doubt there have been outbursts of fiery or 

 molten matter. The gneiss, or metamorphic rocks, to the 

 south of Caithness have all veins of quartz and veins 

 of red granite. These veins are thought to have been 

 molten or hot, and injected into them. Of course, their 

 action was to change the nature of the rocks into which 

 * The Houses of Parliament form an instance. 



