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1. Was there an Ice Age?
Yes. There was a time when glaciers covered large areas of North America and northwestern Europe.1 Most scientists believe there were several ice ages, but some creationists suspect there was only one Ice Age, with fluctuations that produced the appearance of more than one. Ice caps still remain in Antarctica and Greenland, along with many glaciers in the Northern Hemisphere.
There are several lines of evidence that show the presence of ice sheets over much of northern North America in the past. This evidence includes moraines, glacial polish and large boulders known as erratics. Glaciers tend to flow downhill, very slowly. As the glacier moves, more ice is added to the glacier’s head, so the glacier may appear to the causal observer to be stationary. Glacial movement scrapes up rocks from the ground surface and pushes them to the sides and front of the glacier, forming piles of unsorted rock debris. The rock piles along the sides of the glacier are called lateral moraines, while the one at the tip of the glacier is called a terminal moraine. When glaciers move over solid rock, they leave scars in the form of scratches or glacial polish. A glacier may carve a U-shaped valley into the mountains as it moves. Large boulders that fall onto the surface of the glacier will be carried downhill, sometimes for many miles. When the glacier melts, the large boulder, known as a glacial erratic, may be deposited far from its source. These and other glacial features are common over large areas of Canada and parts of the northern United States, showing that these areas were once covered with ice.
2. When was the Ice Age?
Probably not long after the Flood. Many records point toward climatic cooling and establishment of glaciers in the Northern Hemisphere in the uppermost Pliocene,2 which is near the top of the geological column. This would fit well if at least the upper Cenozoic is post-Flood. A lapse of time between the release of the animals from the ark and the onset of the Ice Age would provide time for the animals to disperse across the northern continents before the ice accumulated enough to block further dispersal.
3. Why doesn't the Bible say anything about the Ice Age?
The Bible records the history of the people who preserved the knowledge of the promised Messiah. The Ice Age is not relevant to that history. On the other hand, references such as Job 38:223 may indicate a cooler climate in early biblical history.
4. What caused the Ice Age?
There have been many conjectures about the cause of the Ice Age.4 From a creationist perspective, one of the most interesting models5 was developed by M.J. Oard. In this reconstruction, the ocean was still warm immediately after the flood. This means much water would evaporate and produce precipitation, especially along the storm track of the eastern coast of North America. This storm track brought large amounts of snow to northern North America, where the greatest buildup of ice occurred. As the earth’s crust adjusted to the changes caused by the Flood, earthquakes and volcanic activity occurred. Volcanoes ejected dust and sulfates into the air, which blocked the sun and kept the summers cool. This increased the amount of precipitation and reduced summer melting of the snow and ice.6 As the ground became covered with snow, it reflected more of the sun's heat instead of absorbing it. This cooled the air even more, accelerating the cooling process. After several hundred years, the ocean had cooled sufficiently that the amount of new snow declined. Volcanic activity declined also, allowing the summers to become warmer and melting the ice.
5. How long did the Ice Age last?
In a short-age model,7 the Ice Age might have lasted less than 1000 years. Most geologists believe several ice ages were separated by warmer periods over hundreds of thousands of years. An ice core taken from the Greenland ice sheet was interpreted to show more than one hundred thousand annual layers,8 while an Antarctic ice core was interpreted to record climate changes for the past 740,000 years.9 More research is needed to improve interpretation of the ice cores, taking into account the mobility of materials in the ice sheets,10 the potential for multiple layers per year produced by multiple storms11 and the effects of partial near-surface melting.12
6. How did the Ice Age affect the plants and animals?
The Ice Age affected plants and animals in several ways. First, as the climate cooled, climatic zones shifted toward the equator. Species had to move with their climate zone, become adjusted to a different climate, or go extinct. There are numerous examples of all three responses.13 For example, wooly mammoths adapted to the cooling climate in northern Asia by growing long hair. A few mammoths were trapped in mud and snow, and their bodies preserved for thousands of years, waiting to be discovered and studied by scientists.14 There are no longer any native elephants in northern Asia, as the wooly mammoth is now extinct.
The Ice Age also affected the ability of organisms to disperse to new areas. As ice accumulated on the continents, so much water was lost from the ocean that sea level was reduced by about 100 meters (330 feet). The lowering of sea level exposed land bridges, such as those linking Asia with North America, southeastern Asia with the islands of the Sunda Shelf, Australia with Tasmania and New Guinea, and others. This permitted land dispersal in areas that are now separated by the sea. As the ice sheets grew across North America, they formed a barrier to land animals and plants, making it difficult for species to disperse between Asia and North America. As the ice sheet melted, the climate warmed, and species were able to migrate northward.
7. What about other Ice Ages in the geologic column?
Other "Ice Ages" have been proposed, based on interpretation of certain geologic evidence such as sediment types thought to be typical of glacial activity.15 However, the evidence for pre-Quaternary "ice ages" is more fragmentary, and alternative interpretations for some of the data have been proposed.16
8. What are the most significant unsolved questions regarding Ice Ages?
How and how quickly did the ice sheets form and how did they affect the movement of humans and terrestrial animals? What processes account for the appearance of large numbers of layers in ice cores and cyclical oscillations in climate proxies from marine and terrestrial records?