SOUFEIEEE, AND ON A VISIT TO MONTAGNE PELEE, IN 1902. 
361 
rate, sometimes containing blocks 20 or 30 feet in diameter, and nearly always full of 
bombs and ejected fragments a foot across or more. These beds are red or brown in 
colour, and are jJrincipally andesitic or basaltic in composition. As a rule, their 
bedding is very rough, many thick masses showing only faint and inconstant bedding 
planes several feet apart. Splendid sections of these agglomerates are to be seen 
along the leeward coast, where cliffs several hundred feet high are built up entirely 
of such materials (see Plate 22, fig. 1). It gives the impression that in the Antillean 
volcanoes violent explosive action has been far more frequent than the outpouring of 
streams of lava, and that the recent eruptions are in this respect typical of the 
region to which they belong. But when we compare the Ijeds of ash which have 
been laid down during the present year with those of older date which may be traced 
in the cliff* sections, we are led to the conclusion that in comparison with former 
convulsions this last is a pigmy affair. 
The possibility that in these thick masses of coarse volcanic ejecta we may have 
the remains of former craters—necks, dissected and exposed in the cliff’s by the 
erosive action of the sea—is one which at once suggests itself to the mind of the 
observer. But nowhere did we see a section which could be regarded as that of a 
typical neck, whether j^lugged by agglomerate or by crystalline rock. Wherever the 
structural relations of these masses of coarse ash to the surrounding rocks were well 
seen, they proved to be those of thick irregular beds, lenticular in character, and 
passing laterally into thinner and more uniform sheets. The rapid variation in 
coarseness of material when traced aloiio- the strike, the irreg-ular thickness of the 
beds, and the imperfect development of the bedding planes, together with the 
absence of fossiliferous intercalations, are best explained on the supposition that we 
are dealing with a series of purely sub-aerial volcanic deposits. The rarity of necks is 
partly a consequence of the simple character of the Antillean volcanoes, as exemplified 
by the Soufriere and several others recently extinct ljut still well preserved—where 
parasitic or lateral craters are exceptional. 
Further evidence of land conditions is furnished by the numerous sections of old 
stream-valleys in the agglomerates (see Plate 22, fig. 1). Some of these are well 
shown in the cliffs iieai' Cumberland, a little north of Chateaubelair. Deep gullies 
have been cut out of the beds of ash, and these have been filled up with material, 
which at the sides slopes steeply towards the centre of the trough, while in the middle 
the bedding j^lanes are fiat or slightly concave. Some of these valleys must have 
been veritable gorges, deep and narrow. A peculiar volcanic conglomerate, composed 
of blocks weathered out of the old ash beds or lava streams, but water-worn and 
well rounded, is the deposit which usually occupies them. It is easily recognised 
after a little practice, as it is very different in appearance from the purely volcanic 
tuffs. The sorting action of running water is often exemplified in these con¬ 
glomerates. Some beds consist almost entirely of large, well-rounded boulders, while 
others are much finer grained, and composed of sandy sediment deposited by gently 
VOL. cc.—A. 3 A 
