56 



J. TF. Judd — On Vokanos. 



200 yards broad ; and we can perhaps best give an idea of its true 

 character by describing it as a slightly-curved ridge of cinders, 

 stretching from north-west to south-east, in tbe former of which 

 directions it presents its greatest elevation and steepest slopes, while 

 in the latter it gradually and almost insensibly sinks into the plain. 



On ascending the hill, it is at once seen to be composed of basaltic 

 scorite, often containing olivine, mingled with larger or smaller 

 quantities of fragments of the mica- schist and quartz of the plat- 

 form on which it stands. But the best idea of the structure of the 

 hill is obtained by means of the large artificial excavation that has 

 been made in its southern part. This is a quarry about 200 feet 

 long, 80 feet wide, and 30 feet deep, from which the scorise are dug 

 for covering the roads. It is known as the Zwergeloch (Pigmies' 

 Hole) from the tradition that it is the scene of nightly assemblies 

 and revels of the dwarfs. 



The sides of this quarry exhibit beautiful sections showing that 

 the mass of the hill is composed of basaltic scoriae of remarkably 

 fresh appearance ; but scattered among these are angular fragments 

 of clay-slate, mica-schist, and quartzite, often exhibiting a burnt 

 appearance, and not unfrequently of a bright-red colour. The whole 

 mass is beautifully stratified (as is so commonly the case with 

 the materials of volcanic cones), the varying colours of the different 

 bands giving rise to a very striking appearance. Occasional beds 

 occur, of varying thickness, which are almost wholly composed 

 of fragments of the subjacent rocks ; these we may refer without 

 doubt to the action of sudden explosions tearing away the sides of 

 the vent. Many of the scoriae entangle numerous small fragments 

 of the metamorphic rocks, but the proportion of these entering into 

 the composition of the cone is not nearly so great as in the case of 

 many of the Eifel. The scoriae vary in size from that of a pea, or 

 even less, up to a yard in diameter. A few well-formed " bombs " 





c d c d 



Fig. 2. — Section seen in side of the Zwergeloch. 

 o, a. stratified Basaltic scoriae, 



b, b. Bands made up of fragments of burnt slate. 



c, c. Stratified Basaltic scoriae. 



d, d. Pseudo-dykes occupying lines of fault. 



occur, but do not constitute any large part of the whole, which con- 

 sists mainly of very rugged scoria. A number of small faults or 



