Mr Hugh Miller on Boidder-Glaciation. 177 



more floury material. The residue chiefly consisted of 

 quartz-grains, grains of shale and coal, and some bits of 

 iron pyrites. The specimens figured in the woodcut are all 



^ 



Fig. 7. 

 Microscopic Boulders. 



of quartz, except the smallest, which consisted of a green 

 serpentinous-looking mineral, extremely lithographic, and 

 beautifully turned and striated. They have the lobate form 

 of the glaciated boulder, with one end more pointed and the 

 other squarer or blunter. Even they seem in some cases to 

 have been launched forward end-on, as if in the path of least 

 resistance, and to have the striae passing straight along the 

 back, and bulging slightly out around the sides. And in 

 some instances I thought I detected firmer striae upon the 

 point of the little boulder than upon its broader end. 



Granule- Gla ciation — How A ccomplished. 

 All this seems to point to glaciation within the matrix. 

 " The blacksmith, let him use what strength of arm he may, 

 cannot bring his file to bear on a minute pin or nail until he 

 has first locked it fast in his vice." And why else were the 

 almond-sized boulders glaciated not in contact with each other 

 or with the rock but by the granules of the matrix ? 



Fluxion- Structure in Boulder-Clay. 

 At the corners of streams in boulder-clay districts it is 

 usual to find slipping scars of boulder-clay that in wet 

 weather are turned into streams of slow- running paste. 

 When these are examined — say in summer, when hard baked 

 — it is found that a rude structure has been developed by the 

 movement. The streaming of the particles has steered the 

 stones round until pressure is equal on both sides. Their 



VOL. VIII. M 



