The walls of the caldera consist of fault scarps that have formed as a result of down-sinking of the caldera floor. Much of the caldera floor is covered by lava flows erupted since the 19th century. The Kīlauea Caldera and neighboring Kīlauea Iki are circled by Crater Rim Drive, an long paved road that provides access to Hawaiʻi Volcanoes National Park. The Hawaiian Volcano Observatory was established on the rim of the Kīlauea Caldera in 1912.