@Roberta,
I don't know either, not meant badly by me. Actually, I made it up.
Besides, we lived in the Bronx for a year. 3240 Henry Hudson Parkway, 6th floor. I can still visualize the day we drove away. I think I remember going under some sort of light tunnel, not really a tunnel I think, just looking at the concrete wall (whatever) for the last time... on our way to Chicago. I'd just turned nine.
I never took geology, which I regretted at time (no time).