Mr Hugh Miller on Boidder-Glaciation. 1 75 



II. — Fluxion-Structures. 



Longitudinal Striation of Stones in the Till. 



It is one of the most characteristic features of the boulder- 

 clay that all its almond-shaped or spindle-shaped boulders 

 are striated longitudinally. 



" If the force of water could have scratched and furrowed 

 them," says a writer whom I need have no hesitation in 

 quoting, "it would not have scratched and furrowed them 

 longitudinally, but across. Stones when carried down a 

 stream, or propelled upwards on a beach by the waves, pre- 

 sent always their broader and larger surfaces to the moving 

 force. . . . They are not launched forward, as a sailor 

 would say, end-on, but tumbled forward broadside. They 

 come rolling down a river in flood, or upwards on the shore 

 in a time of tempest, as a hogshead rolls down a declivity. 

 In the boulder-clay, on the contrary, most of the pebbles that 

 bear marks of their transport at all were not rolled but slidden 

 forward in the line of their longer axes. They were launched 

 as ships are launched in the line of least resistance, or as an 

 arrow or javelin is sent on its course through the air." ^ 



I am acquainted with the writings of only one of that 

 famous Scottish school of geologists to whom it fell first to 

 study and debate the boulder-clay, who, mainly through the 

 perversity of his views on the subject, hit upon what I con- 

 ceive to be to a large extent the rationale of this fact. 

 " Although the clay," says Fleming, " was sufficiently dense 

 to retain the boulders floating confusedly in its substance, it 

 was fluid enough to admit of motion." 2 



Striation hy means of the Matrix. 



It appears certain that many of the smaller boulders were 

 slidden along and glaciated in their place in the clay. The 



1 Hugh Miller, On Peculiar Scratched Pebbles, etc., in the Boulder-Clay 

 (Brit. Ass. Report, 1850, p. 94). 



2 Lithology of Edinburgh, p. 61. Fleming held to the last by the "mud- 

 wave " theory. He does not appear, however, to have observed the fluxion- 

 structures. 



