I was walking on a street very near where I live when I came across a startling sight. The neighborhood is very proper New England with clapboard houses and white picket fences. One of the lots, however is missing a house and instead has a house-sized boulder sitting where one would expect the house to be. Order of magnitude, it weighs about a million pounds.

Turns out it’s a glacial erratic, made of 200 million year-old diabase that was pushed down by ice from the outcrops of the Sleeping Giant which lies about five miles due north.