Our current climate is a warm period after successive coverings of ice. The increase in ice 3 million years ago may have been a significant factor leading to the evolution of humans.

When hikers, or others would look at the piles of rocks and rubbles seemingly in the middle of nowhere there was no explanation as to how they got there.

In the early 1800’s geologists were divided into 2 groups. Catastrophic changes and uniform changes. The catastrophic group thought the layers and different species could be explained by relatively recent events such as a great flood and that God would create the new creatures after such events. Uniformists believed that the earth in the past must have behaved much as the earth does today. To explain the layers of rock and fossils it required much longer periods of times.

The idea that giant sheets of ice covered much of North America and Europe took a lot of effort and evidence to be believed and eventually to become the accepted model.

The journey to acceptance required a lot of work, measurement, math and ideas from many scientists. Calculations of the eccentricity the orbit of the earth, the wobble the access showed that we should have ice age periods every 18,000 and 23,000 years.

These were backed up by deep sea bed core samples, which accumulated 3 millimeters a year in some places. We should be going into another glacial period now, but maybe we have been saved from it by global warming.