Geological evidence includes rocks, glacial paleontological. The chemical drumlins, valley cutting, and the deposits of sediments. moraines, evidence looks at the variations in the ratios of Salopes in fossils found in sediments, sedimentary rocks and evidence looks at the cores. ocean sediment Paleontological distribution of fossils. During cold changes in the geographical organisms spread into lower latitudes and time periods, organisms that preferred warmer climates became extinct These types of evidence have shown there were glacial periods over the past few million years. What is the history of ice ages? There have been five major ice ages that chronicle the Earth's past Huronian (over 2 million years ago). Cryogenian (about 850-630 m on years ago). (about 460-420 million years ago), Karoo (360- Andean-Saharan 260 million years ago) and the Quaternary Ice ages (the current ice age starting about 2.58 million years ago).What happens during glacial time periods? The climate is cooler and dryer over most of the Earth. Large land and sea ice masses extend outward from the poles. Mountain glaciers extend to lower elevations due to a lower snow line. Sea levels drop because large volumes of water above sea level are removed from the ice caps ocean circulation patterns are also disrupted. What theories are thoro to explain the ice ages? There are many theories behind the ice ages. -One theory is that the increase of ice and snow causes the earth to reflect more of the sun's energy and absorb less energy. When air temperatures decrease, ice and snow fields grow. -Another theory hypothesizes that an ice-free Arctic Ocean leads to increased snowfall at high latitudes. -Yet, another theory surrounds the concentrations of carbon dioxide and methane.