528 Karl A. Grönwall. 



Of these, a) and b) appear to pass into each other, but the 

 silicified limestone does not seem to have any definite connection 

 with the other more pure limestones, but can very well derive its 

 origin, however, from some limestone of approximately similar char- 

 acter. 



The coarse-grained limestone is gray in colour, often dark-mottled, 

 in consequence of the fact that a part of the fragments of fossils, 

 especially brachiopod spines, of which it contains a fairly large 

 number, are almost black. Of smaller-sized fossil-fragments, it con- 

 tains crinoid stems, fragments of bryozoa and brachiopod spines, 

 the latter being probably the most numerous. The fme-grained 

 limestone is lighter in colour, and has often a yellow-grayish tinge, 

 and contains considerably more of a crystalline matrix than the 

 coarse-grained. Here, of the smaller fossil fragments the brachiopod 

 spines diminish greatly in numbers, the fragments of bryozoa pro- 

 bably playing the more important rôle. 



The silicified limestone when freshly broken is dark gray in 

 colour, sometimes almost black, while on weathered surfaces it is 

 usually buff, with darker fossil-fragments, especially bryozoa of the 

 genus Fenestella. In the fracture it is almost dense and flint-like, 

 so that it is astonishing that, under the microscope, this rock proves 

 to have originally been a rather coarse-grained limestone which has 

 been altered by later infiltrations of silica, hi its general appear- 

 ance, this rock may very well agree with the coarse-grained lime- 

 stone found here, but the fossil contents are somewhat different and 

 so are the structural details. Under the microscope this rock proves 

 to consist of numerous fragments of fossils in a very scanty matrix 

 containing only inconsiderable calcite, and consisting mostly of 

 chalcedon in aggregate-polarizing masses. The fossil-fragments which 

 are, partly, of a fairly considerable size, are crinoid stem-joints (in 

 a majority), parts of bryozoa and brachiopod spines; they have not 

 become silicified but the calcite substance they contain is unaltered. 



In addition to the brachiopods, these rocks contain but few 

 forms of preserved fossils, although fragments occur very numerously. 

 The two limestone species contain about the same fossils, of which 

 may be noted Alveolites sp. and a bryozoan with a very wide and 

 prostrate zoar}'. In the silicified rock, the genus Fenestella Is fairly 

 numerous. The fossil contents of these rocks are about the same, 

 both from the Mallemukfjæld and from the Eskimo Naze. 



These rocks present a certain resemblance to certain rocks 

 occurring in the carboniferous deposits of Spitzbergen ; thus, certain 

 fragments of the coarse-grained limestone resemble the Spirifer lime- 

 stone of Lovén's Mountain on the Hinlopen Strait, and the silicified 



