443 GEORGE F. BECKER 
part I never could succeed in getting slaty structure at the cores 
of the fissile mass. 
In the interest of geology and of active geologists it is most 
desirable that a decision as to the origin and nature of slaty 
cleavage should be reached as soon as possible, and I am in hopes 
that this sketch of my theory may at least promote discussion 
of the whole subject. GEORGE F. BECKER. 
U. S. GEOLOGICAL SURVEY, 
Washington, D.C., January 1896. 
