PSEUDOBRECCIATION IN ORDOVICIAN LIMESTONES 417 
Some of the difficulties in the way of the hypothesis may be 
referred to. A sea bottom in which a calcareous mud is gradually 
Fic. 6.—Dolomitized area with core of calcite. Border undolomitized. X31 
accumulating would not provide the rocky bottom necessary for 
algae in any way comparable to the laminaria of our seas; and a 
wt 
