Clay dogs

Clay dogs are naturally occurring clay formations that are sculpted by river currents from glacially deposited blue-gray clay and then dried by the sun. They exhibit tremendous variety in shape and size, with some being simple and others having highly complex forms. They only occur in a few places in the world; until recently, Croton Point along the Hudson River produced them, but the clay slope that produced the dogs was subsequently demolished to extend a park lawn. ^[1] Clay dogs were described in detail in an article by L. P. Gratacap, Opinions on Clay Stones and Concretions. ^[2]

References

1. ^ Jacobs, Jane. The Death and Life of Great American Cities (1961)
2. ^ http://www.jstor.org/stable/2450388?seq=1