i6o The American Geologist. nav^-h, 1905 
the late elevation, etc., somewhat more fully than in the 
former one, and one point may be added ; namely, his cita- 
tion of Prof. Edward Forbes, showing that the flora of the 
south and west of Ireland gives evidence of former con- 
nection w^ith Spain. 
Another paper deals with the more scanty evidence 
off the west coast of Africa and in the Mediterranean. Be- 
yond the strait of Gibralter, the continental platform loses 
much of its importance, or sometimes disappears and passes 
into a more gradual slope to 1,200 fathoms. "This slope in 
all probability consists of a succession of minor terraces 
breaking off in cliffs." But to determine this requires more 
soundings. Opposite the strait and between Morocco and 
the Canar}- islands, there is a broad terrace of 50-60 miles 
between 600 and 1,000 fathoms. It may represent a shelf 
indicating a long pause in the process of elevation or de- 
pression of the crust of the earth. It is illustrated in a sec- 
tion. At other points tlie declivity is steep as off Europe, 
with the base of the slope at 2.000 fathoms or more. Prof. 
Hull describes to a further extent the canyon of the Congo, 
so systematically worked out by Buchanan as to leave no 
doubt' of its river-like form. But this has already been 
mentioned in America by ^Ir. Upham and the reviewer. 
Hull traces it to a depth of 7,200 feet, in a distance of 122 
miles. Another submarine valley off the coast of Guinea 
(here the shelf is 40-50 miles wide), also described by Buch- 
anan, is called the "Bottomless pit," of like character with 
that of the Congo, surveyed because of the breaking of 
cables in crossing it. There is not sufficient information to 
work out canyons for the Niger and Orange rivers, but they 
should be expected. Here the slope of the great declivity 
is very steep. About this time, Mr. Henry Benest pub- 
lished his replica of the Congo valley, worked out in fine de- 
tail off Cape Verde islands from special cable surveys, 
where the soundings were taken close together for the pur- 
pose of discovering the valley. 
Referring to' the ^Mediterranean, Prof. Hull says that 
while a late relative elevation of the land and sea occurred 
to the extent of 7,000 or 8,000 feet, it must have influenced 
the bordering countries and the Mediterranean, but he 
