242 | THOMAS C. BROWN 
the accompanying diagram and photograph (Figs. 3, 4). Here the 
pebbles are seen to be arranged in unsymmetrical wavelike or 
ripple-like structures which traverse the limestone. In this cut 
the beds are exposed at right angles to these wavelike structures 
and the arrangement is brought out with almost diagrammatic 
clearness. Each series of waves is confined to its own particular 
stratum of the limestone. When the wavelike layer of flattened 
pebbles arches up to form an unsymmetrical anticline the fine- 
Fic. 3.—Photograph of a thin conglomerate layer in place, near Bellefonte, Pa. 
grained material fills the space beneath the anticline down to the 
prominent bedding plane below. The space between the upper 
surface of this pebble layer and the next overlying prominent 
bedding plane is also filled by fine-grained material, which thickens 
over the synclines and thins out over the anticlines. 
The explanation offered for these structures is this: The 
sediments composed of fine-grained calcareous mud resulting from 
the grinding-up of calcareous organic structures by wave action 
and broad flat pebble-like bodies which were the skeletons of cal- 
