393 



shows that no such violence could possibly have operated on the 

 mass. 



3. While in the localities referred to the majority of the peb- 

 bles have the oblong shape and parallel arrangement above 

 described, there are many scattered through the mass which 

 are either nearly round or have their longer dimensions more or 

 less transverse or even perpendicular to the general direction. 

 As these could not have escaped the enormous all-pervading 

 softening action and pressure which the hypothesis assumes, their 

 presence in these discordant conditions seems of itself a sufficient 

 refutation of the theory. 



In regard to the curved form and close adaptation observed in 

 some of the pebbles, Prof. Rogers thought that accidental peculi- 

 arities of shape in the original fragment, and the effects of attrition 

 and the close packing of the accumulated deposit, furnished an 

 adequate explanation both of the bent form sometimes met with 

 and the accurate fitting of the contiguous pebble to the concave 

 surface. 



As an example of the formation of flattened pebbles by the 

 action of the shore waves, Prof. Rogers referred to the paving- 

 stones of slaty trap recently imported from Newfoundland, which 

 are remarkable for their very uniform circular outline, their 

 smooth, slightly convex faces, and a thickness rarely exceeding 

 one third of their breadth. If we suppose a great mass of these, 

 as they lie piled along the shore with their broad sides horizontal, 

 to be hereafter cemented together as a stratum of conglomerate 

 rock, would not the argument founded on their shape and position 

 be even stronger than in the case of the Newport conglomerate ? 

 Yet nothing is more certain than that they owe their shape and 

 arrangement to the peculiar movement and attrition to which 

 they have been subjected by the action of the waves. 



Thus, as regards the Newport rocks and most other conglomer- 

 ates which had fallen under his notice. Prof. Rogers saw no diffi- 

 culty in referring the form and arrangement of the pebbles to the 

 familiar agencies above indicated. He does not, however, doubt 

 that in some highly metamorphic districts conglomerate rocks are 

 to be found which have sustained great internal changes through 

 the effects of heat, chemical action, and violent pressure. Such 



