A later model presents more details. Io consists of a continuous stack of mafic and ultramafic deposits. After new erupted volcanic materials cool down and are buried, the stack of rocks become indurated and form bedrocks. The bedrocks are fractured due to tidal flexing, compression at depth, volcanic intrusion and other mechanisms, and then are broken into large blocks a hundred kilometers across. Products of magmatism like sills, dikes and batholiths may intrude into layers of stacking volcanics to form a composite crust. Occasionally, the large blocks of crust are rotated and thrusted along deep-rooted thrust faults. This process may expose a cross-section of crust to the surface, as at Euboea Montes. Later, these blocks can also be eroded by mass wasting and reburied by subsequent volcanism. At the base of the crust, materials are met again by heat. Compression at depth due to global burial and subsidence can also form ductile deformation like folding of crust.