These are natural bricks of sorts. I found them on the north shore of the Far Away Island, where a seam of clay is visible in the cliff. The “blue clay” is part of the muck of the late Pleistocene glacial deposits that make up the island. The same stuff makes up the long island of Paumanok, underneath me right now. But these stones are obviously not just clay. Somehow the clay has fused together into a solid, albeit friable, form. I haven’t figured out how yet.
Is there a geologist in the house?