388 The Afncricati Geologist. December, 1899 
CORRESPONDENCE. 
On Some Fragments of Slate Found Floating on the Sea in 
Southwest Patagonia.* 
B}' Ekland Nokdenskjold. 
During our stay, in the latter part of the month of April, 1899, on a 
branch of Ultima Esperanza, a channel extending far inland from the 
Pacific ocean in southwest Patagonia, Dr. O. Borge and the author 
made the following remarkable observation. 
While out on row-boat trips for collecting planktons and for fish- 
ing, we saw floating on the water, which was quiet or only very gently 
disturbed, small pieces of slate gathered into rafts of varying sizes. 
They were driven to and fro near the edge of the water, until carried 
away by a strong current which now and then came close to the shore. 
What great quantities of these rock fragments floated about can be 
readily appreciated from the fact that in skimming the surface with 
nets for only two or three minutes 700 pieces were taken in. 
The rock fragments had evidently been floated out from the shores, 
for the beach gravel consisted in the main of the same kind of ma- 
terial, washed down as a disintegration product from the steep and 
thoroughly weathered beach wall that consisted of a bituminous slate 
of Mesozoic age. 
On being touched the fragments would sink, becoming wet on their 
upper surface, where they otherwise were dry while floating. The 
same evidently happens when the water is perturbed by strong wind. 
In this manner a considerable quantity of the disintegrated product in 
the talus of the sea cliffs must be transported in this place. Great 
numbers of rock fragments float out from the shore, either to land on 
the shore again or later to sink in the water at varying depths, where 
thus a peculiar deposit will be formed consisting of pieces of Meso- 
zoic slate mingled with the remains of plants and animals of the pres- 
ent age. 
Besides the slate, floating particles of feldspar were also noticed. The 
pieces of slate have a specific gravity of 2.71. The specific gravity of the 
water in the channel is 1.0049 (i5°). The largest fragment which I 
collected by skimming weighed 0.8 grams. Twenty of the smaller 
pieces had an average weight of 0.3 grams. The slate contains only 
a small amount of bituminous material and includes no vesicles of 
* Under the above title an interesting account is given in Geolog- 
iska' Foreningens i Stockholm Forhandlingar for May this year, of a 
phenomenon akin to, if not identical with, that described by professor 
F. W. Simonds in the January number of the Geologist for 1896. un- 
der the heading Floating Sand: An Unusual Mode of River Trans- 
portation. Believing that Nordenskj old's account will interest the 
geologists of this country. I herewith present it in translation from the 
Swedish, leaving out references to a figure which accompanies the 
original and which shows a small collection of the floating bodies. J. 
A. Udden. 
