In central Idaho, those are in a huge rock formation. They are all empty and range in size from say 6"(not really sure on the small side) up to about 24" across and deep.
I was thinking that maybe some kind of rock or mineral was inside here many years ago and it is gone now or it was something else but evaporated or something.....maybe aliens! I don't know!
If they are actually `tubes' that go on in significant distances, perhaps getting smaller in diameter - the I would suspect that they are due to what is called `piping' (internal tubes of erosion). If they only go in a ways and then there is a nest of some kind - then some critter or bird made them. So, how far in did they go? I imagine piping during a very wet period.
I highly doubt critters made those. The sand is gone, animals only move it around and there are no mounds or trails and besides there are way too many. I would bet my best remmington those are from wind erosion
It's tough to tell from just one photo. But I suspect your first inclination may be right -- inclusions of something softer that weathered away. Given the location, it's hard to say from just one photo whether it's sandstone or volcanic (i.e. ash or pyroclastic). Eastern Washington and Idaho are full of examples of volcanic eruptions on an enormous scale, and the stripe across the middle leads me to think we may be looking at at least three rapid laydowns rather than sedimentary rock in the classic (river/seabed) sense.
I came across something like this while walking a creek this weekend. Large limestone ledges along the bank had 8 - 10 inch size holes and the hole were filled with dirt. Probably erosion and depositing when the water is high. So I'll go with water erosion on your holes also.
The consistancy is like sandstone. I have another pick of a place where the water running down the rock created a (verticle) dry river bed from top to bottom in the rock. I'll post it here. The pic is sitting sideways.....sorry.
I have done everything possible to get my kids involved in hunting. Every time out whether it be scouting, camping or during the actual hunt, I will challenge them to find their way back without using any electronics (GPS). Also without a compass. They know by now that I am going to challenge one of them, so right off the bat when leaving our vehicle or camp they will start picking out land marks to help them out. Makes me and them feel confident that if we were to somehow separate that they...