NEW FORMS OF CONCRETIONS 
By HENRY WINDSOR NICHOLS 
SAND-CALCITE CONCRETIONS FROM SALTON, CALIFORNIA 
A series of five sand-calcite concretions (Museum No. G, 1301) 
presented to the Museum by Mr. Herbert Brown of Yuma, Arizona, 
appear worthy of description. Regarding the conditions of the occur- 
rence of these concretions little is known. Mr. Brown simply states 
that they were handed him by a commercial traveler as having 
been obtained by him at Salton, California. As there are extremely 
large sand dunes in the immediate vicinity of Salton, it is probable 
that the concretions were formed in these. Whether or not the form 
represented by the specimens at hand is a common or an unusual 
type in that locality is unknown. These concretions (Plate XIX) 
are formed of sand cemented by calcite, and are, therefore, of the 
'_ type of the well known Fontainebleau and Saratoga Springs concre- 
tions, from which, however, they differ in several respects. The Salton 
concretions take the form of an irregularly botryoidal ball from which 
projects a stout, tapering stem in such wise that the object assumes 
the shape and proportions of an ancient mace. The change from 
head to stem is abrupt, much as if the stem were driven into a hole 
bored in the head, and there is even a slight annular depression in the 
latter where the stem enters. The botryoidal appearance of the head 
is due to a compound structure — each head being built up from a 
number of spheroidal concretions grown together. While there is but 
little flattening of the concretion as a whole, the subordinate spheroids 
are much flattened and also elongated in the line of the principal axis 
of the concretion. The specimens have a very rough surface from 
the presence in large numbers of rhombohedral points of arenaceous 
calcite crystals. These points suggest that these concretions, like 
those from Devil Hill, Wyoming, described by Barbour,* are aggre- 
gates of moderately large crystals. Lines of stratification (PlateXIX) 
intersect the specimens in such a direction as to ind cate that the 
principal axes lie conformably with the strata in which they form. 
* Bull. Geol. Soc. Amer., Vol. XII, p. 165. 
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