Question

1. what is the likely cause of alternating glacial and interglacial periods?

Explanation:

The Milankovitch cycles are a likely cause. These cycles involve changes in Earth's orbit (eccentricity), axial tilt (obliquity), and precession. These orbital variations affect the distribution of solar radiation reaching Earth. During glacial periods, there is less summer solar radiation in the Northern Hemisphere (due to orbital changes), which allows snow and ice to accumulate. In interglacial periods, more summer solar radiation in the Northern Hemisphere melts the ice.

Answer:

The Milankovitch cycles (changes in Earth's orbit, axial tilt, and precession) are a likely cause of alternating glacial and interglacial periods.