Chapter 2

Aqueous and igneous rocks--General characters of the sedimentary rocks--Mode or formation of the sedimentary rocks--Definition of the term "formation"--Chief divisions of the aqueous rocks--Mechanically-formed rocks, their characters and mode of origin--Chemically and organically formed rocks--Calcareous rocks--Chalk, its microscopic structure and mode of formation--Limestone, varieties, structure, and origin--Phosphate of lime--Concretions--Sulphate of lime--Silica and siliceous deposits of various kinds--Greensands--Red clays--Carbon and carbonaceous deposits.