34 
The American Geologist. 
January, 1896 
might have been anticipated, owing to the evaporation of the 
water, many of the grains had become stranded on the sides 
of the vessel, yet quite a number were still floating. 
How far sand will float is another question difficult to ans¬ 
wer. Mr. Graham records his observations on the Connecti¬ 
cut river sands as follows : “ These blotches were so numerous 
as to be very noticeable in rowing up the river and could be 
traced for half a mile or more below the bank, though this 
bank from which the sand came was but a few yards long.”* 
I have not followed the Llano river rafts for so great a distance, 
though I have, with difficulty, traced them along the bank on 
several occasions—once for more than a hundred yards, when 
by the rippling of the current and the reflections of small 
waves caused by a slight breeze, they were lost to view. If 
the liquid is agitated to such an extent as to break the surface 
and to wet completely the floating grains much of the sand 
will drop to the bottom, though I have found that in a small 
vessel some grains have remained floating after a considerable 
stirring with a glass rod and after repeated shaking or 
jarring. At a point, where a portion of the river had separa¬ 
ted from the main stream and the water flowed quite rapidly, 
I started several series of rafts. As the velocity of the cur¬ 
rent increased and the ripples became stronger the adhesion 
between the grains weakened until the rafts, as such, disap¬ 
peared, though individual particles continued to be seen for 
some distance farther. Such being the case we may expect 
that whenever a stream passes over any irregularity in its 
channel, such as rapids, even if very small, or waterfalls, the 
floating sand will sink, indeed such a result may be looked 
for when the surface is disturbed by a wind. 
Before proceeding further, I wish to say that the Llano river 
sand is not an extremely fine sand, but, on the contrary, rather 
coarse. The grains are not, however, of uniform size. While 
some are small, many are comparatively large. The follow¬ 
ing measurements of four selected quartz grains will serve to 
indicate, approximately, the size of those that float: 
*Loc. cit. 
