Item A shows a Lava source going through the Mantle and Crust, rising above Sea level to surface labeled Hawaii. Item B shows the Mantle beginning level on the left and dipping down on the right; the Crust is level on the left, labeled Great Valley of California, with mountains on the right, labeled Sierra Nevada and Mount Whitney. How is Item A different from Item B? The crust under the ocean in Item A is thicker than the crust under the mountain in Item B. The mantle under the ocean in Item A is thinner than the mantle under the mountain in Item B. The crust in Item A is found partially below sea level as compared to the crust in Item B. The mantle in Item A is located far below a mountain as compared to the mantle in Item B.