https://en.wikipedia.org/wiki/Louis_Agassiz#Ice_age
https://www.britannica.com/biography/Louis-Agassiz
But what does not appear on the Agassiz page, on Wikipedia, or Britannica, is that he stole it from Karl Shimper
This knowledge does appear, in a brief way, in the Karl Schimper article
https://en.wikipedia.org/wiki/Karl_Friedrich_Schimper
This remarkable paper published 50 years after gives a wonderful account of the whole sordid matter.
https://archive.org/details/jstor-25101263/page/n1/mode/2up
Just beautiful writing in that old text, thanks to archive.org for saving it from obscurity
It's mentioned in