A88 W. J. SOLLAS ON THE SILURIAN DISTRICT 
angular siliceous particles or true sand-grains, or, it may be, with 
impure argillaceous mud. 
Fig. 4.—General Section of the Silurian Beds in the Cardiff Area ; 
thicknesses from the Rhymney River Exposure. 
Old Red Sandstone. 
Grit-bed, containing fish-remains. 
Upper Ludlow. 
Wenlock Limestone. 
i Thin band of bluish limestone. 
Ferruginous concretionary bed. 
Rhymney grit. 
| Unknown ground; on Pen-y-lan side, 
greenish-grey mudstones and siliceous 
sandstones, with red shales and mud- 
stones in the middle. 
Greyish-green mudstones and argillaceous 
sandstone. 
