8l6 MYRON L. FULLER 



etched pebbles (Fig. 2, A) upon the flat surface of a frag- 

 ment of conglomerate which, judging from its shape, was a part 

 of a much larger bowlder which had split apart along the etched 

 surface. This seemed to indicate an internal etching along a 

 bedding plane, but could not be regarded as conclusive. Further 

 search, however, brought to light bowlders several feet in diame- 

 ter in which etched bedding planes could be traced through the 

 mass of the rock. Because of the thickness of the bowlders, 

 specimens of the etched surfaces were difficult to obtain, but the 

 character of the etching in a sandy portion of the rock is shown 

 in the illustrations B and C of Fig. 2, which are from photo- 

 graphs of specimens taken from opposite sides of an etched 

 plane extending through a bowlder of some size. Not only 

 are the surfaces strongly pitted by the complete removal 

 of a portion of the grains, but under a glass the individual 

 grains, even those of the smallest size, exhibit distinct evidences 

 of etching, either by distinct pittings, or by the general "ground 

 glass appearance" of their surfaces. 



Still further examination brought to light evidences of etch- 

 ing within quarried blocks at distances of five feet or more from 

 the surfaces, but in these cases the etching was confined to the 

 immediate vicinity of plant remains, now carbonized or changed 

 to coal, and, so far as could be detected, was not connected with 

 either etched or unetched bedding or joint planes. The etching, 

 though distinct, was not of the pronounced type characterizing 

 many of the bedding planes (Fig. 2, A), but was more of 

 the character shown by the illustrations B and C of the same 

 plate. 1 



The etching, so far as noted at Blossburg, was confined to the 



bedding planes or to the vicinity of the vegetable remains in the 



1 Specimens of quartz pebbles from the Carboniferous conglomerate of Ohio 

 showing strong impressions of plant stems, were exhibited at the Cleveland meeting of 

 the American Association, in 1853, by Professor Jehu Brainerd. These impressions, 

 as urged by Professor J. S. Newberry, were probably due to the action of humic acids 

 evolved during the decay of the vegetable matter, and appear to be of the same nature 

 as the etching about the plant remains in the conglomerate at Blossburg. (See Jehu 

 Brainerd, Origin of the Quartz Pebbles of the Sandstone Conglomerate and the For- 

 mation of Stratified Sand Rocks, Cleveland, 1854, p. 16; and J. S. Newberry; Ohio 

 Geol. Surv., Vol. II, Pt. I, 1874, p. ill. 



