A main support pillar designed to withstand the bulk of overhead weight
A main support pillar designed to withstand the bulk of overhead weight
Timbers laid at right angles to each other to create a vertical or horizontal support structure
A wide crack, fissure or opening in rock
A period existing 146-65 million years ago
A stabilized part of the Earth’s crust, usually centrally attached to the continents
A circular depression created by a sunken volcanic vent in the ground, or meteoric impact