CHAPTER VII.

STRATIFIED ROCKS OF CHEMICAL ORIGIN.

Chemical Agency employed in the Formation of Mechanical Rocks--But some Rocks produced almost exclusively by the Action of Chemical Laws--Difference between a Mixture and a Solution--a Saturated Solution--Stalactites and Stalagmites--Fantastic Columns in Limestone Caverns--The Grotto of Antiparos in the Grecian Archipelago--Wyer’s Cave in the Blue Mountains of America--Travertine Rock in Italy--Growth of Limestone in the Solfatara Lake near Tivoli--Incrustations of the Anio --Formation of Travertine at the Baths of San Filippo and San Vignone, 109