ocr: caldera : - / 6 eruption of - - - : - - - a ash-flow tuffs 6 miles silicic magma chamber arrerentiation and reacuon with wall rock V - nising silicic magma . - of basaltc magma Cheat CRUST partially melts crust 24 MANTLE A basaltic magma cham ber miles rising of basaltic magma above denser rock 40 miles 10 miles magma o.ongnation ofbasaltic Generalized vertical cross secuon ofSnake River Plan shows possible origin of basaltic and silicic rock and the manner in which volcanic rocks reach the eart's surrace (modified after Leeman, 1982).
