SILICEOUS OOLITES IN PENNSYLVANIA 265 
our knowledge of these bodies goes there is not so intimate a rela- 
tion between the external form and the molecular structure as there 
is in crystals, there must be some relation on a larger scale, though 
less perfect, and it is probable that when concretions are more fully 
understood it will be found that their structures, like those of 
crystals, are all developed according to definite laws. 
4 
Frc. 4.—Photomicrograph of siliceous odlites imbedded in a chert ground mass. 45 
ORIGIN OF THE SILICEOUS OOLITES 
Two theories have been suggested for the origin of the siliceous 
odlites. In his article on ‘‘Eopaleozoic Hot Springs and the Origin 
of the Pennsylvania Siliceous Odlite,’”* Dr. Wieland endeavors to 
show that they originated in the siliceous waters of hot springs. 
His statements, however, indicate a very limited knowledge of the 
rock, since he states that it occurs over an area of one square mile 
t Am. Jour. Sci., ath ser., IV (1897), 262. 
