Marilyn Burgess, age 15, of Asheville, N.C., for, her question:

What is the geological reason for no snakes being in Ireland?

In the remote past the world wide climate was warm and balmy, and snakes crawled contentedly over all of europe, including what is now Ireland. Then the ice ages Came, and massive glaciers inched down from the Arctic over much of the northern hemisphere. Snakes are reptiles, and reptiles cannot abide the cold. All the snakes in northern europe perished.

As they came and went, the massive glaciers changed the face of the earth. New arms of the sea flooded in to cut off England and Ireland from the continent of europe. Many animals driven south by the ice returned as it melted, but snakes are poor travelers. A few of them managed to reach England. But after the ice ages, none of them were able to cross the sea and return to Ireland.