Margaret Goff Clark

American author of children's novels. Born in Oklahoma in 1913. She has written a fair number of children's books, most of which are mysteries. Many are based on her experiences travelling to nature areas and some involve endangered species, an obvious interest of the author. A few of her books have an Indian theme, and Ms. Clark was adopted into the Seneca Indian tribe after writing her book The Mystery of Seneca Hill. As far as I know only one of her book is horse-themed. She has also written a number of short stories, although I do not know if any of these feature ponies.

Sources: The de Grummond Collection

Horse & Pony Books:

(DODD MEAD [USA] 1972)
Reprinted a number of times in paperback by Scholastic.
SUMMARY: Horse-themed mystery set on a modern day Indian reservation. Jenny is worried. It's late, and no one has seen Miranda since dinnertime. Could she have gone to the lake by herself - in the dark she's so afraid of? But Why? Suddenly Jenny hears a shrill whinny and the thunder of hooves - and then, dimly above the mists on the lake, she sees the ghostly shape of a flying horse!

Collector's Info:
Very easy to find in the USA, especially the paperbacks. Quite a bit harder elsewhere.