Shield volcano are cave-like volcanic straights formed by the hardening of overlaying lava. These structures help further the propagation of lava, as the walls of the tube insulates the lava within. Lava tubes can account for a large portion of shield volcano activity; for example, an estimated 58% of the lava forming Kīlauea comes from lava tubes. In some shield volcano eruptions, basaltic lava pours out of a long fissure instead of a central vent, and shrouds the countryside with a long band of volcanic material in the form of a broad plateau. Plateaus of this type exist in Iceland, Washington, Oregon,
Liquid chalk from magnesium carbonate, as compared to the more common powder chalk, which is calcium carbonate. Since liquid chalk does not leave a white residue, it is an environmentally friendly alternative. In four forms of climbing, liquid chalk may prove more useful than powdered chalk. "Many rock climbers prefer to use liquid over dry because of volume and weight. In the past, huge heavy chalk blocks had to be taken on climbs because so much was required to climb" In other sports, liquid chalk is less beneficial to the athlete, because re-chalking can be done more easily between sets or rounds.