Question

which evidence originally supported hesss idea of seafloor spreading in 1968? younger rocks are closer to mid - ocean ridges. the destruction of crust occurs at deep - sea trenches. oceanic rocks are pillow - shaped when formed. rocks across the ocean floor have alternating magnetic stripes.

Explanation:

Seafloor - spreading theory posits new oceanic crust forms at mid - ocean ridges. Younger rocks being closer to mid - ocean ridges shows new crust is forming there, supporting Hess's idea. The destruction of crust at deep - sea trenches is related to subduction, not the original evidence for seafloor spreading. The pillow - shaped form of oceanic rocks is a characteristic of their formation but not key evidence for spreading. Alternating magnetic stripes are a later confirmation.

Answer:

Younger rocks are closer to mid - ocean ridges.