TERTIARY FORMATION. 657 
a series of rhombohedrons. ‘This is seen in the first of the following 
figures, which may be conceived of as made by the superposition of 
Fig. 1. Fig. 2. 
one rhombohedron upon a face of another in a continued series. It is 
a kind of interrupted crystallization, resulting in producing a rhombic 
prism or lengthened rhombohedron, which is farther obscured by a 
gradual diminution of the prism toward either end. ‘The extremities 
are turned a little in different directions in consequence of this mode 
of formation, and in the same manner as the prisms from Glendon. 
The Glendon prisms differ in nothing except their having a smoother 
exterior, a result of more uniform crystallization. The granular 
interior is evidence that the crystals have undergone some change 
since their formation; but what is the nature of that change remains 
to be explained. 
The following is the result of an analysis of one of these concretions, 
by Prof. B. Silliman, Jr. 
Carbonate of lime, - : = 93°60 
Carbonate of magnesia, - E : 1°65 
Oxyd of iron and alumina, - - 1:55 
Sand, - c - c = 2-20 
Water, - - - - : 0-60 
Loss, - - - = 5 : 0°40 
Fosstls.—The shale, in the vicinity of Astoria, contains numerous 
fossils. ‘Those to the eastward are imbedded in calcareous nodules, 
and are consequently well preserved, while those in the cliffs down 
the river lie unprotected in the shale, and have suffered from com- 
pression. The specimens collected include numerous shells of mol- 
165 
