I've been thinking about White Mare, and found this aerial photo online. It is from Uffington, in the Berkshire Downs in England. It is 3000 years old, and now maintained by The British Trust. One of several such chalk carvings in hills in England, this is the largest, at 374 feet in length.
I'm adding this picture I painted a few years ago. It is based on a drawing by my daughter Willa, who was five when she drew it. Myra Josong mentioned it in a comment, and by Georgia, she's right. There is a powerful similarity.