opportunity should we fail to again quote Prof. Todd for an explanation
of the cause of the vivid coloring. Commencing he says: "Newton remarks
concerning this:[4] 'A large percentage of peroxide of iron in the red
beds, to which they owe their bright red color, bears an interesting
relation to the absence of fossils. The material of which sediments are
formed is derived, by the various processes of denudation, from the
rocks of older land surfaces. Whatever iron they contain is dissolved
from the land and transported in a condition of protoxide and some proto
salt, such as the carbonate, and the process is facilitated by the
presence of carbonic acid in the water. Now iron occurs in these older
rocks as protoxide and peroxide, the former of which is soluble and the
latter insoluble in water. The peroxide, however, by the action of
organic matter, such as is held in solution in boggy waters, may be
deprived of a portion of its oxygen and converted into protoxide and
thus be rendered soluble. If the iron-bearing water is confined first in
a shallow basin and exposed long to the action of the atmosphere the
protoxide of iron absorbs the oxygen and is precipitated as an insoluble
red peroxide of iron. If, however, plant or animal life be present in
sufficient quantities, this oxidation is prevented. In case but little
foreign material, clay or sand, has been brought by the waters, the
deposit will be an iron ore. In case large quantities of foreign
material are deposited from the waters at the same time, there will be
produced, in the absence of life, a brown or red clay or sandstone, and
in its presence a white or light colored formation containing the iron
as a carbonate. We reason therefore from the condition in which the iron
is found in the red beds, that there could have been little or no life,
animal or vegetable, in the water from which it was deposited. The
conclusion is strengthened by the fact of the large quantities of gypsum
which are usually derived from the evaporation of saline waters. The
degree of saline concentration which the precipitation of gypsum