Tertiary—the oldest [period] of the [Cenozoic] era; follows the [Cretaceous] period of the [Mesozoic] and precedes the [Quaternary] period of the Cenozoic.
Test—the protective covering of some invertebrate animals.
Theca—a sheath or case; in coelenterates, the bounding wall at or near the margin of the [exoskeleton]; in echinoderms, the main body skeleton (or [calyx]) which houses the animal’s soft parts; in graptolites, any cup or tube of the colony.
Thorax—in trilobites, that part of the body between the [cephalon] and pygidium.
Time-unit—a portion of continuous geologic time (e.g., eras, periods, epochs, and ages).
Time-rock unit—same as time-stratigraphic unit.
Time-stratigraphic unit—term given to [rock] units with boundaries established by geologic time; strata deposited during definite portions of geologic time (e.g., systems, [series], stages, etc.).
Topography—the physical features or configuration of a land surface.
Topographic map—a map showing the physical features of an area, especially the relief and contour of the land.
Transverse—at right angles to length.