Subject ASC000117f

The Quarterly journal of the Geological Society of London.
v.56 (1900), Page 447 (1900)
Smithsonian Libraries
BHL Page 41487799

Keywords

Geology Silurian Lower Ludlow fossils graphtolites graphtolite zones geography geology lithology lower ludlow rocks zone ludlow district builth disctrict long mountain district dee valley lake district shales geological Ludlow Rocks Lower Ludlow Rocks geographic geographical variation monograptus tumescens scanicus nilssoni vulgaris Builth district wenlock limestone lower coldwell graphtolite

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