722 F. E. WRIGHT EFFECTS OF GLACIAL ACTION IN ICELAND 



ever, the direction of the spur itself practically coincides with that of the 

 ice-flow. Under these unique conditions the sides of the spur are not 

 only aligned in both valleys, but its ridge is greatly reduced and ground 

 down by the confluent overriding ice currents. After recession of the ice, 

 it appears as a low, gently sloping, drawn-out tongue of bedrock point- 

 ing downstream and separating the two valleys to their very junction, 

 where it passes into the valley floor. At the same time its effect is to 

 merge the two valleys and to render their junction less abrupt. In case 

 this type of glacial junction spur occurs between fiord extensions of 

 glacial valleys, it reaches out as a low, gently sloping peninsula, and 

 finally passes beneath the water. Occasionally a series of small islands, 

 each elongated in the direction of ice-flow, appear, and are simply the 

 higher parts of the continuation of the junction ridge under water, as 

 indicated by soundings. On passing inland, these glacier junction spurs 

 or ridges rise gradually and increase in width until finally their slope 

 becomes abruptly steeper and leads, then, rapidly up the main mountain 

 mass. The decrease in the slope of the ridge of a glacier junction spur 

 toward its seaward tip is characteristic. The crest itself is not always a 

 smooth line, but is usually undulating and irregular after the manner of 

 hummocky glaciated rock floors. Such glacier junction spurs are typi- 

 cally developed between Fljotdalur and Laxardalur, in north Iceland, 

 and between the converging branches of the Hvita, in Myrar, west Ice- 

 land.* In southeastern Alaska they also occur frequently, notably near 

 the head of Lynn Canal, at the junctions of Taiya, Chilcoot, and Chilcat 

 inlets. 



Glacier junction deposits. — At the junction of all large tributary val- 

 leys, the normal flow of the trunk glacier is more or less disturbed; 

 jamming of the ice results, and produces deflection and stoppage of sub- 

 glacial drainage, conditions to which peculiarly shaped gravel deposits 

 and mounds, as well as the irregular valley bottom at such points, now 

 bear witness. In Laxardalur, Adalreykadalur, and Eyjafjardardalur 

 such deposits are especially abundant. 



^ear the mouth of Vatnsdalur, where the valley enters the wide low- 

 land area south of Hunafjordur, a group of irregular, often conical, 

 shaped hills occur, from 50 to 75 meters in height, and composed entirely 

 of glacial material, each hill being of different composition and size of 

 material. Altogether these deposits cover an area of possibly 2 square 

 kilometers. Unfortunately, no time was available, in passing, to study 

 them more closelv and their mode of formation was not ascertained with 



* Unfortunately rainy and foggy weather prevented the writer from securing satis- 

 factory photographs of the glacier junction spurs of this region. 



