THE OLD RED SANDSTONE. 235 
It is the part of the chemist to tell us by what peculiar ac- 
tion of the organic matter the dye was discharged in these 
spots and: patches. But how was the dye itself procured ? 
From what source was the immense amount of iron derived, 
which gives to nearly five sixths of the Old Red Sandstone 
the characteristic color to which it owes its name? An ex- 
amination of its lowest member, the great conglomerate, 
suggests a solution of the query. I have adverted to the large 
proportion of red-colored pebbles which this member con- 
Old Red Sandstone remarked by Professor Fleming as early as the 
year 1830, and the remark reiterated by Dr. Anderson, of Newburgh, 
in nearly the same words, but with no acknowledgment, ten years 
later. The following is the minute and singularly faithful description 
of the Professor : — 
“On the surface of the strata in the lower beds, circular spots, 
nearly a foot in diameter, may be readily perceived by their pale yel- 
low colors, contrasted with the dark red of the surrounding rock. 
These spots, however, are not, as may at first be supposed, mere su- 
perficial films, but derive their circular form from a colored sphere to 
which they belong. This sphere is not to be distinguished from the 
rest of the bed by any difference in mechanical structure, but merely 
by the absence of much of that oxide of iron with which the other 
portion of the mass is charged. The circumference of this colored 
sphere is usually well defined; and at its centre may always be ob 
served matter of a darker color, in some cases disposed in concentric 
layers, in others of calcareous and crystalline matter, the remains 
probably of some vegetable or animal organism, the decomposition of 
which exercised a limited influence on the coloring matter of the sur - 
rounding rock. In some cases [ have observed these spheres slightly 
compressed at opposite sides, in a direction parallel with the plane of 
stratification — the result, without doubt, of the subsidence or con- 
traction of the mass, after the central matter or nucleus had ceased 
to exercise its influence.” —-(Cheek’s Edinburgh Journal, Feb. 1831, 
p- 82.) 
