338 GlESECKfe ON THE MINERALOGY OF DISKO. 



such an extent, that rivers are often impeded in their course, and 

 the whole neighbourhood laid under water. Over this amygdaloid, 

 a mass of ferruginous clay occurs, similar to the '' Eisenthon " of the 

 Germans, which approaches to the jaspery oxide of iron. This is 

 again covered by amorphous basalt, separated from columnar 

 basalt, which usually forms the summits of these hills, by another 

 seam of the same ferruginous substance, of a brownish colour. 



The mountain called Ounartorsak, near Godhavn, presents the 

 following proportions in one of its precipices : — 



Basalt, 1 Basalt, in columns of from three to seven 

 columnar. J sides, with some crystals of felspar. 



1. 



2. 

 3. 

 4. 

 5. 

 6. 

 7. 



[> Eeddish-brown ferruginous clay. 



] Amorphous basalt, with geodes 

 J mesotype. 



> Reddish-brown ferruginous clay. 



Basalt, ] Amorphous basalt, with geodes of radiated 



amorphous, j mesotype. 



Amygdaloid. 1 Reddish-brown wacke, containing stilbite, 

 J mesotype, &c. 



Basal't-Lk } '^^® ^^^* ^^*^ apophyUite, &c. 

 ' > Granite, with gneiss. 



All the basalt of Disko is magnetic. That found in the most 

 elevated situations is most so ; the fallen masses dispersed around 

 the base of the mountains having more power over the needle than 

 the others. 



The mountains of Disko are almost all flat at the top, and at a 

 distance present the appearance of large houses. It was only in 

 the Waygat, and in the Bay of St. James (Omenaks Fiord), 

 where I observed pyramidal and conical summits. Mannik, a 

 mountain in Waygat, is terminated by an immense basaltic pyramid 

 of four sides. 



On the summits of all the mountains which I ascended, I ibund 

 numerous rolled masses of Primitive rocks, often of considerable 

 size, and of a weight beyond my power to move. These masses 

 consisted either of granite, gneiss, mica-slate, siliceous schist, 

 quartz, or hornstone. 



Porphyry-slate is the rarest' rock among those of the Trap- 

 formation in Greenland. I ascended several of the mountains, 

 but I found it only in two, Unknown Island and Hare Island, 

 to the north of Disko ; and there it occupied only the summit, in 

 tables split into a thickness varying from six inches to two, af- 

 fording a clear ringing sound when struck by a hammer. The 

 Greenlanders informed me, that during tempestuous weather, even 

 at the foot of the mountain, they often heard tones resembling 

 those of music, and that Tornarsuk, their good and evil deity, 

 when enraged, was the cause of them. He never, however, hap- 

 pened to be out of humour within my hearing. 



At the foot of this immense Trap-formation of Disko, consider- 



