en and interrupted than the other
two, and a greater proportion of its vents are extinct. It attained its
condition of maximum activity during the distant period of the Miocene,
and now appears to be passing into a state of gradual extinction.

Beginning in the north with the volcanic rocks of Greenland and Bear
Island, we pass southwards, by way of Jan Mayen, Iceland and the Faroe
Islands, to the Hebrides and the north of Ireland. Thence, by way of
the Azores, the Canaries and the Cape de Verde Islands, with some active
vents, we pass to the ruined volcanoes of St. Paul, Fernando de Noronha,
Ascension, St. Helena, Trinidad and Tristan da Cunha. From this great
Atlantic band two branches proceed to the eastward, one through Central
Europe, where all the vents are now extinct, and the other through the
Mediterranean to Asia Minor, the great majority of the volcanoes along
the latter line being now extinct, though a few are still active. The
volcanoes on the eastern coast of Africa may be regarded as situated on
another branch from this Atlantic volcanic band. The number of active
volcanoes on this Atlantic band and its branches, exclusive of those in
the West Indies, does not exceed fifty.

THIAN SHAN AND HAWAIIAN VOLCANOES

From what has been said, it will be seen that the volcanoes of the globe
not only usually assume a linear arrangement, but nearly the whole of
them can be shown to be thrown up along three well-marked bands and the
branches proceeding from them. The first and most important of these
bands is nearly 10,000 miles in length, and with its branches contains
more than 150 active volcanoes; the second is 8,000 miles in length, and
includes about 100 active volcanoes; the third is much more broken and
interrupted, extends to a length of nearly 1,000 miles, and contains
about 50 active vents. The volcanoes of the eastern coast of Africa,
with Mauritius, Bourbon, Rodriguez, and the vents along the line of the
Red Sea, may be regarded as forming a fourth and subordinate band.

Thus we see that the surface of the globe is covered by a network of
volcanic bands, all of which traverse it in sinuous lines with a general
north-and-south direction, giving off branches which often run for
hundreds of miles, and sometimes appear to form a connection between the
great bands.

To this rule of the linear arrangement of the volcanic vents of the
globe, and their accumulation along certain well-marked bands, there a