Dinosaur, an order of extinct reptiles, of which there were a dozen varieties, mostly lizardlike and of huge size.

Exhume, to dig out of the ground, or in the case of a fossil, to take out of its place of burial in the rock.

Faulted, interrupted continuity of rock strata by displacement along a plane of fracture, generally caused by an earthquake.

Formative, the era of the birth and growth of the earth out of the spiral nebula of the sun, the beginnings of the atmosphere and hydrosphere, and of the continental platforms and ocean basins.

Fossil, the remains of plants and animals of prehistoric times, now found embedded in the rocks.

Psychozoic, the era of man, including the time during which man attained his highest civilization (perhaps the past 30,000 years), to the present.

Geology, the history of the earth as read in the rocks.

Geyser, a boiling spring which periodically sends forth jets of water, steam and gas.

Glacier, a slow moving river of ice, remnant of the last ice age, generally found flowing down the mountain peaks.

Granite, a granular rock consisting of quartz, mica and feldspar,--the material of the original crust of the earth.

Gypsum, the mineral from which plaster of Paris is made.

Ichthyosaurus, an extinct fishlike reptile of huge size.

Igneous, produced by the action of fire (i.e., a rock).

Jura.s.sic, that period of the Mesozoic era that gave rise to birds and flying reptiles.

Lava, the melted rock ejected by a volcano.

Limestone, a rock due in the main to the acc.u.mulated debris of plants and animals, especially to the sh.e.l.ls of marine animals.

Lithosphere, the rocky crust of the earth.

Mesozoic, the era of reptile dominance, in which occurred the rise of dinosaurs, birds and flying reptiles, flowers and higher insects, and primitive mammals.

Metamorphic, recrystallized by heat (i.e., a rock), or changed by pressure.

Metamorphose, to change into a different form.

Miocene, that period of the Cenozoic era when apes were transformed into man.

Paleozoic, the era of fish dominance, in which occurred the first abundance of marine animals, the first known fresh-water fishes, the first known land floras, the first known amphibians, the first insects and the first acc.u.mulations of coal.

Proterozoic, the age of invertebrate dominance, containing an early and a late ice age.

Reconnaissance, a preliminary survey.

Scarp, declivity.

Shale, a fine-grained, layered, sedimentary rock, generally easily crumbled.

Silica, a form of quartz.

Stalact.i.te, a pendant cone of calcium carbonate deposited by dripping water (as in a cave).

Stalagmite, a deposit (on the floor of caves) resembling an inverted stalact.i.te.

Strata, layers of rock or earth.

Striated, marked with fine grooves or lines of color.

Tria.s.sic, the period that gave rise to dinosaurs.

Triceratops, a fossil giant lizard.

Uplift, an upheaval of rock strata.