Geologists are not anthropologists nor archaeologists. And core samples differ in many parts of the world and some interpreted differently. From core samples we have learned that the last ice age was not the first and definitely not the last. Global warming has also been found in core samples everytime right BEFORE a major climate shift occurs such as an ice age. Global flooding can mean regional flooding if it happens at the same geological period in time at many places around the globe. Thats how mankind survived the floods of "Biblical Proportion". In MY view, The Bible speaks metaphorically of what science says in theory. There is no way for any of us to know EXACTLY how or where these things happened as we can only make educated guesses as none of us were there. Geology does wonders to help archaeology and vice versus, but there are not many exact sciences out there as many things in this world are open to interpretation.
We know the last ice age is not the first and won't be the last because the Earth does just change temperature for no reason. It was correctly assumed that ice ages occur for a similar reason that seasons do.
The Earth's orbit has eccentricity (the Earth's orbit changes from ellipse to circle every 100,000 years), obliquity (the Earth's axis of tilt changes from 21.5 degrees to 24.5 degrees every 41,000 years), and the precession of the equinoxes (which is the wobble in the Earth's rotation that occurs in a 26,000 year cycle). The combination of these effects was worked on in 1920 by Milutin Milankovitch who combined the effects of obliquity, eccentricity, and precession of the equinoxes on the amount of solar heat received at different latitudes for the past 1,000,000 years. He argued that the greatest change in the amount of solar heat received occurs at 65 degrees north.
A low summer allowed snow to accumulate during the year. When the maximum temperatures remained low, the ice built up. He predicted the last ice age was 10,000 years ago.
The ice core samples only verified his claims. But ice ages weren't "discovered" because of ice core samples. Interestingly enough, Italian scientist Cesare Emiliani took samples of foraminifera and compared two isotopes of oxygen - oxygen-18 and oxygen-16. When the temperature of the water drops, the foraminifera use oxygen-18 to build their shells and when the water temperature rises, they use oxygen-16.
In ice ages, evaporation from the oceans decreases so as time progresses, the heavier oxygen-18 stays in the water because it is heavier than oxygen-16. So when it is colder, the forams use oxygen-18.
If you plot solar radiation at 65 degrees N with the ratio of oxygen isotopes in the foraminifera, you find they are coincident.
So it is wrong to say that we know the last ice age was not the first and won't be the last from core samples. Orbital theory has much more to do with it.