■24 



150 å 200 Meter. ' Fugleberget er maalt til 150 Meter. 

 Ægøen anslaaet til c. 150 Meter. 



Beerenbergs Basis er, som paavist af Carl Vogt, bygget 



af Lavalag og tildels Tuflag. der synes at have flydt eller 

 være kastet ud at det store Central-Krater, sandsynligvis 

 førend dette havde opbygget den ovre Askekegle. At lig- 

 nende Bygning er Øens Midtparti og etter Udseendet at 

 dømme ogsaa den sydlige Del. ( Ivenpaa denne store sam- 

 menhængende Lavamasse staa en Mængde smaa Sidekratere, 

 der for en stor Del have bevaret en udpræget konisk Form. 

 Saadanne ere Krater Sårs, Krateret øst for Sydbræen. 

 Kraterne Esk og Vogt. Kraterne Danielssen og Blytt og 

 Kraterne ved Guineabugten. Forstyrrede i sin Form ere 

 Fugleberget paa Vestsiden og Ægøen paa Østsiden, idet 

 begges ydre Kraterrand er opslugt af Havet. Nogle af 

 Sidekraterne ere byggede af Lava og have udsendt betyde- 

 lige Lavastrømme. som Vogt, Esk, . nogles Top er bygget 

 af løse udkastede Masser. Slakker og Aske. Rapilli. som 

 Kraterne ved Mary Muss Bugten. ved Guineabugten, andre 

 af Tuflag. Tufconglomerater og faste Lavalag, som Fugle- 

 berget, og atter andre af Aske alene, som Ægøen og Berna. 



Den vulkanske Hovedspalte, bvorpaa Jan Mayen er 

 bygget, gaar aabenbart effcer Øens Lrengderetning, efter 

 Heklalinien. Men Sidekraternes Gruppering synes afgive 

 en Antydning af, at der bar været Tverspalter i Retningen 

 WNW. — ESE. Vi have nemlig i denne Retning, som det 

 synes, flere Rader af Sidekratere, saasom Esk — Vogt — Berna. 

 Fugleberg — Egø, Hoyberg — Krater ved Fyrtaarnet (?). Er 

 det et Tilladde, at Endekrateret mod SE. i de to første 

 Rækker, Berna og Ægø, kun have udkastet Aske? 



Af Dale gives der paa Jan Mayen ingen af større 

 Længde; de større Dale paa Nordlandet ere fyldte af 

 Bræerne og Sydlandet synes at være meget lidet indskaaret 

 af Dale. Af Bække ere kun faa iagttagne. 



Karakteristiske fm-. lan Mayens Kyst ere de paa mange 

 Steder opstaaende Klipper i Havet, hvoraf vi ovenfor have 

 nævnt flere. De ere vistnok for storste Delen Rester af 

 Lavastrømme, der ere gaaede ud i Havet. 



Jan Mayens Kyster ere, som ovenfor berørt, paa 



mange Steder meget bratte og bøje. Paa andre Steder er 

 'ler et lavt Forland, bestaaende af Lava. dækket tildels 

 med Sand. Dette Forland, som paa Kartet har sin sær- 

 egne Betegnelse, ligger tildels saa lavt. at det er dækket 

 med Rækved. Lave Strender, af Sand, ere ogsaa mange- 

 steds tilstede, og indeholde store Mængder af Rækvéd, 

 Kjæver og. Hvirvler al' Hval. Vraggods og opkastet Tang. 



reach a height of '400 to 600 feet. The altitude of Fugle- 

 berg we found by observation to be 490 feet; that of Egg 

 Island was estimated at 400 to 500 feet. 



As shown by Carl Vogt. the base of Mount Beerenberg 

 is composed partly of lavers of lava. and partly of layers of 

 tuff. that would appear to have flowed or been discharged 

 from the great central crater previous to ' the formation of 

 the lipper cone of ashes. The middle tract of the island 

 exhibits a similar structure. and to judge from its appear- 

 ance, also the southern part, Above this stupendous mass 

 of lava rise a number of small parasitic craters. the greater 

 part of which have retained a conical form. Such. fm- in- 

 stance. are Sars's crater, the crater east of the southern 

 glacier. the Esk and Vogt craters. Danielssen 's and Blytfs 

 craters, and the craters in the vicinity of Guinea Bay. 

 Fugleberg on the west coast and Egg Island on the east. 

 are no longer conical. the outer edge of the crater ha ving 

 given way and fallen into the sea, Some of the parasitic 

 craters are built up of lava. and would appear to have 

 sent forth considerable currents, as the Vogt and Esk cra- 

 ters; the summit of others consists of loose er upte.d masses, 

 cinders, and ashes (rapilli). as the craters hi the vicinity 

 of Mary Muss Bay and Guinea Bay; others are composed 

 of layers of tuff. tuff-conglomerate and compact masses of 

 lava. as the Fugleberg.' ånd others again of ashes alone. as 

 Egg Island and the Berna crater. 



The chief volcanic fissure in which Jan Mayen Island 

 is built. must obviously extend in the longitudinal direction 

 of the land. parallel to the volcanic line of Mount Hecla. 

 Meanwhile. the grouping of the parasitic craters would 

 seem to intimate the existence of transverse fissures running 

 from WNW. to ESE.; for in .that direction there are. 

 apparently, several rows of parasitic craters. as the Esk. 

 Vogt, Berna. the Fugleberg and Egg Island. Hoyberg and 

 the crater in the vicinity of the -pilot-boat" (?). Must we 

 regard it as mere accident that each of the terminal cra- 

 ters towards the south-east in the two first rows should 

 have discharged ashes alone? 



Jan Mayen has no valleys of considerable extent; the 

 large ravines in the northeru part -of the island are filled 

 with glaciers. and the southern land would appear to be 

 hut little intersected by vaies or ravines. Of brooks oi" 

 rivulets, very few have been observed. 



A characteristic feature distinguishing the coast of 

 Jan Mayen, are the fantastic-shaped rocks that in many 

 places rise abruptly from the sea., of which we have men- 

 tioned several. Thev are no doubt in greater part frag- 

 ments of laVa detached from currents that had flowed into 

 the sea. 



The coasts of .hm Mayen are. as previously stated. 

 in many places lofty aud precipitous. In some localities, 

 however. there is a low expanse of foreshore consisting of 

 lava. partially covered with sand. This foreshore, which is 

 separately marked on the Map, lies so low in places as to 

 be covered with driftwood. Some localities. too, exhibit a 

 low såndj beach, bestrewn with large quantities of driftwood, 

 thejawsand vertebræ of whales, hits of wreck, andsea-weed. 



