622 GEOLOGY OF OHIO. 
abruptly into a very rough and ungainly stone, called “Turtle-back,” or 
*“‘Nigger-head,” by the quarrymen. Their surfaces in such instances are 
generally covered with marks, indicating origin in shallow water. They 
are destitute of lines of bedding, and present rather the appearance of 
concretionary structure than of deposited layers. Such courses are al- 
together valueless as building stone, and are used only for the protection 
of river banks and for other similar purposes. The large amount of waste 
material to be moved in reaching the most reliable and desirable courses 
constitutes the main element in the expense of quarrying. In the Jas- 
per quarries, for example, not more than ten feet of the thirty feet that 
belong to the system can be put into the market as first-class building 
stone. 
Of the many shades of color displayed by the Waverly quarry courses, 
perhaps a light drab can be taken as the standard; at least it is the 
color which is most highly esteemed for architectural purposes. It is 
not, however, an original color of the stone, but has been formed by the 
action of the atmosphere on the external portion of the exposed layers. 
The native color of the beds from which this most approved variety is 
derived is a delicate blue—a little deeper than the shade known among 
painters as French gray. By the oxidation of some of its materials, or, 
possibly, by the removal in solution of a small portion of oxide of iron, 
the change is effected. The very slight difference in composition be- 
tween the weathered, or bleached portion, and the blue stone, is shown 
in the following analysis made by Prof. Wormley. The samples taken 
for analysis were from the quarries of Maurice Reiche, Esq , of Waverly, | 
who has made a very careful study of the building stones of the Scioto 
valley, and to whom the Survey is indebted for much valuable informa- 
tion : : 
No. 1. No. 2. 
(White stone.) (Blue stone.) 
SUITELGLAGCT he orcas sets Won detus sade crear aoe aeunentae saan meecmiees 91.30 91.00 
Protoxide’ Of rome eek eee eke eae eRe nee tan 0.86 iL ily/ 
ROSTSO DUK AKO KE OVE TUONA .crisce doaceG00G 044005 on60d0 800Gb OO eee Ra payaencare 0.06 0.30 
HANTATTNTIN ANS: oe isgacecdece cae seoel eele eee soso ten aa sere crass summer ieauieen 5.79 5.20 
PGVIMWNOeee ie ccialiccee oe cen eces ee coete Sec eee cue a Reet aac ere maietis vette tac stetiata sacs trace trace 
Mia om eSiatojsst ccsscudecessienncedoss sesleccecalusmenelscnsen crest sceslestaestsause 0.32 0.28 
Water COmbINe yew cicos csece sess dosseseetsomccimeceeotese nace 1.30 1.80 
99.63 99.75 
The change from the blue color to the lighter tint has taken place in 
all exposed portions of the rock, but seldom extends inward more than ten 
or twelve feet. As these weathered portions have been first removed, 
not only on account of the desirability in color, but also by reason of 
