24 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 70 



ing and its accompanying phenomena. In western Maryland a fault 

 passing through a Silurian conglomerate was located. The con- 

 glomeratic layer itself at this place was composed of small, rounded 

 pebbles of pure white quartz, forming an interesting educational 

 object in itself, but along the fault zone the conglomerate had been 

 broken into angular fragments and recemented together into a hard 

 rock. In one case this recementation had been caused by silica and 

 in another by iron ore. Large examples of both kinds of this fault 

 breccia, as it is known technically, were quarried out. bVjrtunately, 



Fig. 24. — East front of Alleghany Mountains, Western Maryland, showing 

 fault zone at C. Photograph by Bassler. 



as shown in figure 24, this fault zone (C) outcropped along a good 

 country road, making the problem of quarrying and transportation 

 easy. 



In each of these areas photographs of the occurrence of these 

 specimens in nature were secured so that the ex])lanatory exhibition 

 labels can be illustrated. The object of displa\ing such specimens 

 is not simply to illustrate their geological or paleontological features. 

 biU to show in the same exhibit a portion of geological history 

 involving at least several distinct events. 



