Volcanic activity produces a variety of extrusive landforms when magma reaches the Earth's surface as lava, ash, gases, and other pyroclastic materials. The nature of these landforms depends on the composition and viscosity of magma, the type of eruption, and the duration of volcanic activity. These landforms are important components of geomorphology because they significantly modify the Earth's surface and influence local drainage, soils, and ecosystems. Volcanic cones are among the most common extrusive landforms. They are formed by the accumulation of lava, ash, cinders, and volcanic debris around a central vent. Shield cones are broad, gently sloping volcanoes formed by repeated eruptions of fluid basaltic lava. Because the lava spreads over large distances before solidifying, these volcanoes have low-angle slopes. Mauna Loa and Mauna Kea in Hawaii are classic examples