Question

WHAT EVIDENCE HAVE YOU COLLECTED TO EXPLAIN THE RELATIONSHIP BETWEEN SEAFLOOR SPREADING, MID OCEAN RIDGES AND OCEAN TRENCHES IN 3 SENTENCES

Answer 1

Symmetric magnetic striping and the progressive increase in radiometric and sediment ages of oceanic crust away from mid‑ocean ridges show that new basalt is created at the ridges and then spreads outward (seafloor spreading). High heat flow, shallow seismicity, axial volcanism, and elevated bathymetry at mid‑ocean ridges indicate upwelling mantle and formation of new oceanic lithosphere. Deep ocean trenches, concentrations of deep‑focus earthquakes, volcanic arcs, and the presence of older, denser oceanic crust adjacent to trenches show that this spreading is balanced by subduction, recycling lithosphere back into the mantle and linking ridges and trenches in the plate‑tectonic cycle.