and South Central Pennsylvania. 411 



cian formations is complete without their consideration. 

 In 1916 I published a preliminary paper (10) in which 

 an attempt was made to distinguish between interf orma- 

 tional and intraformational structures, especially in 

 limestone and dolomite, as follows : 



"A review of the literature, as well as of certain examples in 

 the field, has shown that not all intraformational conglomerates 

 are made up of water- worn materials: in fact, certain of them 

 are composed of distinctly brecciated fragments which show no 

 signs of attrition by water transportation, a common character- 

 istic according to most geologists. It may seem strange at first 

 to consider a 'sun-cracked' limestone as a brecciated rock, and 

 yet viewed in cross-section, or at right angles to the bedding 

 plane, the hand specimen or field section will often show a char- 

 acteristic brecciated structure. 



"It is, therefore, proposed to introduce two new terms, Glom- 

 erate and Phenoclast, in describing all those rocks (glomerates) 

 which are of sedimentary origin, coarse, or psephitic in texture, 

 whether or not their "show" constituents (phenoclasts) give 

 signs of attrition and transportation." "Glomerate, according 

 to the Century Dictionary, means ' collected into a spherical form 

 or mass.' It is an old English word and rarely used. Con- 

 glomerate in its ordinary sense is also defined as 'a rock made 

 up of the rounded and water-worn debris of previously existing 

 rocks, etc,' (the italics are the writer's). It is proposed to use 

 the term glomerate in a geological sense to mean any sedimen- 

 tary or clastic rock made up of roughly graded debris formed 

 within itself or from pre-existing rocks. Such a term would 

 cover breccias, conglomerates and certain other rocks of doubtful 

 origin. 



"Nauman, in his 'Geognosie, ' proposed the term Psephite, 

 but it has never been widely accepted, and probably never will 

 be although it is a useful word in petrology." 



"There is as great a need for a term to express the order or 

 size of the constituents in a sedimentary rock as there is for the 

 term phenocryst, which designates a large crystal in the ground- 

 mass of a crystalline rock. Phenoclast, from pheno, show, and 

 clast, clastic, broken piece or fragment, is proposed to designate 

 the larger fragments which are easily distinguished from the 

 ground-mass or cementing material. They, the phenoclasts, 

 may be of several orders of size and shape. The term is conve- 

 nient as it is not always correct to refer to the major constituents 

 of a conglomerate as pebbles, or even brecciated fragments. 

 For instance, in the edgewise glomerates the pebbles and cement 

 are apt to be formed from the same material. Also the shape 

 of the 'pebbles' is hardly pebble-like, neither are the 'pebbles' 

 true brecciated fragments. Their outline is as peculiar and 



