Question

1. which mechanical layer of earth is characterized by rock that is plastic, or soft enough to flow?

Explanation:

The Earth's mechanical layers include the lithosphere, asthenosphere, mesosphere, outer core, and inner core. The asthenosphere is part of the upper mantle, and its rock is plastic (ductile) and can flow over long periods due to high temperature and pressure, allowing the lithospheric plates to move on it.

Answer:

The asthenosphere (part of the upper mantle) is the mechanical layer of Earth characterized by rock that is plastic (soft enough to flow over geologic time scales).