(See figure below, where meiosis I begins with a diploid (2n = 4) cell and ends with two haploid (n = 2) cells.) In humans (2n = 46), who have 23 pairs of chromosomes, the number of chromosomes is reduced by half at the end of meiosis I (n = 23).
Explanation:
Variations in the sun's energy reaching Earth
Changes in the reflectivity of Earth’s atmosphere and surface
Changes in the greenhouse effect, which affects the amount of heat retained by Earth’s atmosphere
Glaciers leave behind deposits known as glacial till, which are unstratified, poorly-sorted sediments. Glaciers move a wide range of sedimentary particles from small clay-sized particles to large boulders. When the glacier either melts or retreats, these poorly-sorted sediments are deposited.
