# Like who came up with the initial idea/ theory and when was it first proven?
In: Planetary Science
I don’t have a lot of specifics, but ice ages (colder periods when ice sheets form further south than they usually do) leave dramatic evidence on the landscape. As time goes on, sheets of ice literally “creep” southwards. Any debris that gets stuck underneath, like rocks and boulders, will get dragged along underneath them. This slowly carves scars into the ground, and the rocks end up very far from where they started once the ice eventually melts. The Great Lakes of North America were actually formed by glaciers cutting basins into the land.
The ice itself also picks up loose dirt, which accumulates. When the ice melts, ridges of dirt remain, and these ridges are called “[drumlins](https://en.m.wikipedia.org/wiki/Drumlin).”
Two other things: ice is *heavy*, and over hundreds to thousands of years the land beneath the ice sheets gets compressed, forming depressions. When the ice melts, the land begins to rebound. We can see this process by looking at how water features like lakes and rivers behaved in the past; lakes will get shallower and shallower as the land decompresses until they’re gone altogether. And speaking of lakes, melting glaciers can form “[glacial lakes](https://en.m.wikipedia.org/wiki/Glacial_lake)” which are *massive* resevoirs. If the glacier itself is holding water in, there is a chance that the resevoir may burst when the ice becomes too thin. The resulting flooding dramatically alters the landscape downstream.
I mean, Google answers a lot of the basic facts in half a second.
The longer story is that we’ve known the Earth’s climate changes for a couple of hundred years. There was a miniature Ice Age from around 1400-1850 by the 1800’s scientists had figured out something was up – global societies had been very obviously altered, a quick example is that China suffered really badly from crop failures during this time which lead to a lot of Chinese interaction with the new “Global economy” for things like New World precious metals and cold tolerant crops (yams very specifically).
Anywho, so my 1850’s European scientists had evidence that the climate changes and then they started observing the effects of global warming as we left that mini-ice age. Glaciers melted and wildernesses were changing in real time and they observed first how glaciation affects the land – carving up mountains, dropping rocks and boulders, etc.
They took those observations and just looked around and realized there was evidence of that, x1,000,000 everywhere they looked. This combined with the knowledge that many animals had gone extinct ‘fairly recently’, things like Mammoths and Irish Elk and European Lions, etc.
So by the mid-1800’s we had solid theories that something “really bad, and really icy” specifically happened during human existence. Our knowledge of geology, the climate, the atmosphere, chemistry, and astronomy have all just refined and polished this theory over time.
The theory of ice ages comes from the Swiss geologist and naturalist Louis Agassiz.
In 1836, he met the geologists Ignaz Venetz and Jean de Charpentier who had both been studying Swiss glaciers and proposed they had once covered much larger areas of the country. De Charpentier had found isolated rocks standing in the countryside (erratics) that resembled the large boulders dumped at the snouts of glaciers as well as banks of rock (called moraine) far from glaciers that looked exactly like the piles of rock found along the edge of glaciers. However, neither Ignaz or de Charpentier could work out how glaciers formed and moved.
Agassiz, working alongside the British geologist William Buckland, studied the uplands of the UK and came to the conclusion that ice had spread from the mountains into the lowlands during a period of great cold. Agassiz pretty much came up with the explanations of how glaciers flow as well as identifying the signs they had once been present – not just erratics and moraines, but also the scratch marks (striations) they leave in the underlying rock. Agassiz and Buckland’s work was published in the UK with the phrase ‘ice age’ appearing in 1837, and he went on to show there were similar signs of glaciation all round the world.
When people started asking questions like: this giant boulder in the middle of a field, hundreds of kilometres from any mountains, how did it get here? Pierre Martel in 1742 is credited for that question, though he was looking at mountain glaciers, not continental ice shelfs. Same mechanism though.
Lots of great answers about modern scientists — but the first humans to discover the ice age were, uh, living through it.
Modern science became aware of Ice Ages in the 19th century, as others have pointed out, however humans lived and evolved through ice ages. There may be some persistant remembrance of it in our mythology, such as the realm of Niflheim.
It is very easy to determine, that there are polar ice sheets and alpine glaciers on Earth which means we are in an ice age. I do not mean there was an ice age recently I mean we are in an ice age right now. The alternative is a greenhouse period with no glaciers on the planet.
What you ask about is that there was a glacial period within the Ice Age with glaciers that advanced and covered are part of Earth. Other posts have explained the evidence of that. The last glacial period ended about 15,000 years ago. We are in an interglacial period within an ice age
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