CHAP. III. ] TENERIFFE TO SOMBRERO. 213 
to separate any organisms it might contain, we put it into jars 
to settle, it remained for days in suspension. 
In indicating the nature of the bottom on the charts, we came 
from experience, and without any theoretical consideration, to 
use three terms for soundings in deep water. Two of these, 
“ol. oz.” and “r. el.,” were very definite, and indicated strongly 
marked formations, with apparently but few characters in com- 
mon; but we frequently got soundings which we could not ex- 
actly call either “ globigerina ooze” or “red clay ;” and before 
we were fully aware of the nature of these we were in the hab- 
it of indicating them as “ gray ooze” (gr. 0z.). We now recog- 
nize the gray ooze as, in most cases, an intermediate stage be- 
tween the globigerina ooze and the red clay; we find that on 
one side, as it were, of an ideal line, the red clay contains more 
and more of the material of the calcareous ooze, while on the 
other the ooze is mixed with an increasing proportion of red 
clay. 
When the section from Teneriffe to Sombrero was taken we 
had not fully recognized the importance of the transition stage, 
and the bottom was marked on the chart “globigerina ooze,” 
or “red clay,” according as one or other gave a distinct and 
marked character to the sounding. The soundings at Stations 
V.and VL, for example, might have been labeled “ gray ooze ;” 
for although its nature has altered entirely from the globige- 
rina ooze, the red clay into which it is rapidly passing still con- 
tains a considerable admixture of carbonate of lime. 
The depth goes on increasing to a distance of 1150 miles 
from Teneriffe, when it reaches 3150 fathoms; there the clay 
is pure and smooth, and contains scarcely a trace of lime. From 
this great depth the bottom gradually rises ; and, with decreasing 
depth, the gray color and the caleareous composition of the ooze 
return. Three soundings in 2050, 1900, and 1950 fathoms on 
the “ Dolphin Rise” gave highly characteristic examples of the 
globigerina formation. Passing from the middle plateau of 
