Subject ASC0001fr0
The Quarterly journal of the Geological Society of London.
v.7 (1851), Page 109 (1851)
Smithsonian Libraries
BHL Page 34984230
Keywords
geology Aix-la-Chapelle divisions lower middle upper uppermost clay greensand chalk-marl gyrolite-greensand Vetschau Kunraed Hornstone measurement feet German Valkenberg and Maestricht geological conifers clay-beds fossils sandstones marine organisms soil layers strata