334 gieseckI: on the geology of Greenland. 



9. The Flcetz Trap-formation of Greenland is perhaps the 

 most extensive that has been discovered. It begins at 69° 14' N. 

 lat., occupies the large island Disko, and the eastern coast of the 

 Waygat, from Niakornak, on the northern cape of Arve-prinz 

 Island, round the Cape Noursoak, as far as the end of the southern 

 coast of Cornelius Bay, where it reaches the continental glacier. 

 Hare Island in the north of Disko Island, Unknown Island in the 

 mouth of Cornelius Bay, the islands Kakiliseit in the north of 

 the latter, and many other northern islands consist entirely of 

 floetz-trap. From thence it extends over a part of the continental 

 coast of Greenland, viz., London Coast, Svartenhuk, JEkalluit, 

 Kangersoeitsiak, Karsorsoak, and disappears in the 76th degree 

 under the most northern continental ice or glacier, which precludes 

 all further investigation. ^ 



The whole Flcetz Trap-formation of Greenland, as far as it has 

 been examined, rests on gneiss or on mica-slate, these rocks 

 alternating continually. The underlying Primitive rocks, as well 

 as the superincumbent Flcetz-trap, are always somewhat decom- 

 posed, where they come in contact. Trap-tuff generally rests 

 immediately upon the Primitive rock ; it consists of balls and 

 nodules of basalt and wacke, joined together by a cement of the 

 same substance ; the centre of the balls and nodules is very often 

 filled with mesotype, blended with massive or crystallised apo- 

 phyllite, the crystals of which are sometimes penetrated by 

 acicular mesotype. This trap-tuff scarcely presents another 

 mineral ; and the apophyllite, or ichthyophthalmite, does not 

 occur there in any other rock. The underlying Primitive rock is 

 very variable in its elevations, sometimes it does not surpass the 

 level of the sea, sometimes (for instance, at Godhavn) it reaches 

 a height of from 500 to 600 feet, which can be observed very 

 exactly in the cliffs there. Columnar basalt lies upon trap-tuff. 

 It presents four, five, and seven-sided columnar distinct concre- 

 tionsp the columns very seldom exceed a foot in diameter. This 

 basalt does not include any mineral, except sometimes very minute 

 spots of greyish-white glassy felspar. Wacke generally rests 

 upon it, forming an amygdaloid with different minerals, viz., 

 chabasite, stilbite, analcime, chalcedony, opal, heliotrope, quartz, 

 zeolite, miemite, and basillar arragonite. At Hare Island the 

 chalcedony is found crystallised in cubes. At Kannioak in 

 Omenaksfiord, miemite occurs in kidneys, along with chalcedony, 

 opal, wavellite, arragonite, and some quartz, in grey decomposed 

 wacke. The wacke of the Flcetz Trap-formation of this country 

 is generally intersected by small veins of iron-clay and bole. 

 Lithomarge and green-earth occur in nodules. Olivine and 

 augite are but seldom met with in the Floetz-trap of Greenland. 

 Laumonite, in a friable state, is found in very small veins, 

 traversing wacke at Sergvarsoit, on the northern coast of Disko 

 Island. Most of the Greenlandish basalt affects the needle very 

 powerfully. There are generally two, and sometimes three strata 

 of columnar basalt, and one of them forms the summit, except at 

 Hare Island, where the summit consists of porphyry -si ate resting 

 upon wacke. The shape of the mountains is very various ; some 



