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How does pillow lava support the idea of sea seafloor spreading?

How does pillow lava support the idea of sea seafloor spreading?

Magma comes out of ocean ridges as pillow lava and forms a new oceanic crust, supporting sea floor spreading. The older crust gets pushed away from the ridge and pushes on to the continents, making them drift.

What are the 4 evidences of seafloor spreading?

Harry Hess’s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory. This evidence was from the investigations of the molten material, seafloor drilling, radiometric age dating and fossil ages, and the magnetic stripes.

Is there any evidence for seafloor spreading?

Evidence of Sea Floor Spreading Harry Hess’s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory. This evidence was from the investigations of the molten material, seafloor drilling, radiometric age dating and fossil ages, and the magnetic stripes.

Where are pillow lavas found in the world?

As described above, pillows form at low, though imprecisely known, flow rates. Pillow lavas have been observed while forming on the shallow submarine slopes of Hawaii, where subaerial lava flows enter the sea, and on W. Mata Volcano, a seamount in the NE Lau back-arc basin (Resing et al., 2011).

Why do pillows stop growing in a lava flow?

Single pillows stop growing when crusts become sufficiently thick to impede inflation. Once pillow growth ceases, failure of the pillow crust leads to the formation of a new pillow at the leading edge of the flow. Alternatively, flow may be redirected within the feeder systems to produce new pillows elsewhere.

How big is the pillow lava in the mantle?

Basaltic magma that rises from shallow depths in the upper mantle is extruded as pillow lavas in the region known as seismic layer 2A (approximately 0.5–1 km thick). The magma may be intruded as sheeted dikes and sills into the underlying layer 2B (about 1 or 2 km thick) or as slow cooling gabbros into layer 3 (about 2-5 km thick).