PUY-DE-DÔME (63) - "Mountains of clay, undermined and degraded by rainwater near ISSOIRE in Auvergne" & "PRISMS, or Columns of Basalt which pass to the state of balls in the PUY DE LA VEILLE". 2 etchings engraved by PIERRON & De MACHY, after the drawings of Cen BESSON. Proofs on wove paper. In Paris, at Basset Md d'estampes rue St Jacques n°670. Good margins for the 2. 29 x 42,5 cm approximately each. A/B condition (some stains in the margins slightly dusted). Set of 2 plates.