UNCONFORMITY: A geologic feature caused by a disturbance (erosion, igneous intrusion, or fault)
UNICELLULAR: Composed of just one cell
UNIVERSAL SOLVENT: A substance that is really good at dissolving a variety of other substances. Water is considered the universal solvent.
UPWELLING: Winds blow surface waters offshore, causing cold, nutrient rich water to come up from below. Upwelling helps recycle nutrients in the ocean. Ecosystems such as the kelp forest and coral reefs rely on upwelling.