Heaps of soil...giant mutant gophers?
I recently noticed several heaps of powdered soil in an unused area of my yard, and I'm puzzled about their origin. Can anyone help me figure out what they are?
Note: each is about 2.5 MB, so if you have a slow connection, download with caution.
My first reaction was "gophers," but there's no evidence of a hole in the center of any of the heaps. Also, they're bigger than any gopher mound I've ever seen.
heap1 is in its original state. For scale, the plant next to the heap is a dwarfed oak tree. The leaves are about normal size for an oak.
heap2 is larger -- probably about a foot across. It was originally taller, but I flattened it by poking in search of a hole (which I didn't find).
The area where the heaps appeared is about 100 square feet. It's surrounded by my house on two sides, and by a concrete patio on the other two. The surrounding soil is dry and compacted. It seems like a very unappealing place for a gopher to dig... even for a giant mutant gopher, if that's what it is.