Norris Geyser Basin has a sweeping, porcelain-like appearance created by smooth sinter deposited through centuries of thermal activity and continually glazed by minerals, hot water, and living microorganisms called thermophiles. Like most geyser basins, it lies lower in elevation than the surrounding terrain, in a bowl or basin. Iron is common here, causing some of the basin’s rust color, and although many Yellowstone thermal features are alkaline, numerous geysers and hot springs at Norris Geyser Basin are acidic.