As the dirt flew and the leaves were placed, I realized I could have been videoing the event, so I hit record for what, as you can see, turned out to be the final seven seconds.* The raven then flew back in the direction it came. In all my years of watching ravens, this is the first time I've seen them caching food.
I called H and we went out to take a closer look. We had to refer to the images on the camera to locate the meat. It was indeed buried under a thin layer of dirt and topped with leaves. It was a good size and largely fat.
It's hunting season, so perhaps someone is butchering somewhere in the vicinity.
* The hazy waving things in the video and the blurry line on the lower right edge of the first pic are the strings hanging on the outside of the window to prevent bird collisions. As you can see, there's a bit of a wind.