condition; rocks of eruption,
p 20
endogenous (granite, sienite, porphyry, greenstone, hyperathene, rock,
euphotide, melaphyre, basalt, and phonolithe); sedimentary rocks (silurian
schist, coal measures, limestone, travertino, infusorial deposit);
metamorphosed rock, which contains also, together with the detritus mica
schist, and more ancient metamorphic masses. Aggregate and sandstone
formations. The phenomenon of contact explained by the artificial imitation
of minerals. Effects of pressure and the various rapidity of cooling.
Origin of granular or saccharoidal marble, silicification of schist into
ribbon jasper. Metamorphosis of calcareous marl into micaceous schist
through granite. Conversion of dolomite and granite into argillaceous
schist, by contact with basaltic and doleritic rocks. Filling up of the
veins from below. Processes of cementation in agglomerate structures.
Friction conglomerates -- p. 269 and note. Relative age of rocks,
chronometry of the earth's crust. Fossiliferous strata. Relative age of
organisms. Simplicity of the first vital forms. Dependence of
physiological gradations on the age of the formations. Geognostic horizon,
whose careful investigation may yield certain data regarding the identity or
the relative age of formations, the periodic recurrence of certain strata,
their parallelism, or their total suppression. Types of the sedimentary
structures considered in their most simple and general characters; silurian
and devonian formations (formerly known as rocks of transition); the lower
trias (mountain limestone, coal measures, together with 'todilegende' and
zechstein); the upper trias (butter sandstone, muschelkalk, and keuper);
Jura limestone (lias and oolite); freestone, lower and upper chalk, as the
last of the flotz strata, which begin with mountain limestone; tertiary
formations in three divisions, which are designated by granular limestone,
lignite, and south Apennine gravel -- p. 269-278.