222 The American Geologist. October, i892 
that the stratum containing the leaves is a part of the Lafayette 
formation, having not been disturbed since its original deposition. 
On this evidence the Lafayette epoch would belong in the Pleis- 
tocene period, instead of the Pliocene, to which it has been pro- 
visionally referred. 
Subinarine valleys on couthicutal slopes. By Warren Upham. 
The submarine fjord of the Hudson river, whose bottom is 2,844 
feet below the sea level, and the similar valleys discovered by 
Prof. George Davidson off the coast of California, one of which 
sinks to the depth of 3,120 feet where it crosses the submarine 
contour line of 600 feet on the continental slope, are surpassed 
by the submerged caiion of the river Congo. This canon, of 
which a description and map are given by Mr. J. Y. Buchanan, 
in the Scottish Geographical Magazine for May, 1887, extends 
about a hundred miles out to sea from the mouth of the Congo, 
and descends to a depth of more than 6,000 feet beneath the sea 
level. Along its last twenty miles before it enters the ocean, the 
Congo has a depth of 600 to 1,450 feet. At the mouth of the 
river the width of this gully, as Mr. Buchanan calls it, is three 
miles, and its depth is 2,000 feet. Thirty-five miles out to sea, 
the width of the gullied submarine valley or caiion is six miles, 
and its depth 3,440 feet. At the distance of seventy miles off 
shore the general slope has fallen off to the depth of 3,000 feet, 
and below this the caiion has an additional depth of 3, 000 feet 
more, the sounding to its bottom being 6,000 feet. Several other 
very remarkable submarine valleys are found on this western 
coast of Africa near the equator. 
Though Mr. Buchanan attributes these submerged canons to 
the action of marine currents setting in landward under the lighter 
fresh water of the river, while the land, according to his belief, 
has held its present relation to the sea level, geologists who have 
studied the submarine valleys of the eastern and western coasts 
of North America will confidently refer their origin in Africa, as 
on our own continental Iwrders, to a formerly greater altitude of 
the land when it stood higher than now by as great an amount as 
the depths of the canons below the ocean's surface. 
That the Congo submarine valley is not yet filled with the al- 
luvial silt of the river, which discolors the surface water to the 
distance of many miles off shore, proves that the subsidence of 
the land from its former altitude was geologically recent. These 
