oil (petroleum)

59:3.4It is in the de­posits of this age that much of the gas, oil, zinc, and lead are found, the gas and oil be­ing de­rived from the enor­mous col­lec­tions of veg­etable and an­i­mal mat­ter car­ried down at the time of the pre­vi­ous land sub­mer­gence, while the min­eral de­posits rep­re­sent the sed­i­men­ta­tion of slug­gish bod­ies of wa­ter. Many of the rock salt de­posits be­long to this pe­riod.

60:3.9The de­posits of chalk and green­sand marl give name to this pe­riod. The sed­i­men­ta­tions of these times are var­ie­gated, con­sist­ing of chalk, shale, sand­stone, and small amounts of lime­stone, to­gether with in­fe­rior coal or lig­nite, and in many re­gions they con­tain oil. These lay­ers vary in thick­ness from 200 feet in some places to 10,000 feet in west­ern North Amer­ica and nu­mer­ous Eu­ro­pean lo­cal­i­ties. Along the east­ern bor­ders of the Rocky Moun­tains these de­posits may be ob­served in the up­tilted foothills.

59:5.16The pres­ence of roots of trees as they grew in the clay un­der­ly­ing the pres­ent coal beds demon­strates that coal was formed ex­actly where it is now found. Coal is the wa­ter-pre­served and pres­sure-mod­i­fied re­mains of the rank veg­e­ta­tion grow­ing in the bogs and on the swamp shores of this far­away age. Coal lay­ers of­ten hold both gas and oil. Peat beds, the re­mains of past veg­etable growth, would be con­verted into a type of coal if sub­jected to proper pres­sure and heat. An­thracite has been sub­jected to more pres­sure and heat than other coal.