Does the spell Earth Tremor require loose stone?

The condition for the second effect of Earth Tremor reads (emphasis mine):

If the ground in that area is loose earth or stone

Loose earth is adequately explained in this question referencing the Mold Earth cantrip.

My question is: does “loose” apply to both earth and stone, or does Earth Tremor’s second effect work on non-loose stone, such as a solid stone floor?