That's a HUGE hole somewhere....or a bunch of moderate sized ones....most of their projects seem to involve clay or mud...commodities they hopefully have an unlimited supply of, since many of their projects seem to involve clay, mud, and holes,
we built stick rooms take sticks or limbs all the same length and stack with clay between rows after you built a circular wall lower at one side than the other you covered the end wood with a layer of mud in and out with a 2 foot doorway you had to turn sideways to get in or out a tarp with cut wood logs tied to the grommets leaving a opening to allow the smoke to go out and a blanket thrown over the door way kept the insects rain if it came out and wind off and the heat in about 10 foot in diameter. Slept 3 people you could stack thorn bushes and limbs with thorns around and the critters would leave you alone. when you left it stacked a bunch thorns in front or, you may have to re-inhabit after a scrap with the new squatters a good smoking got out the bees wasps and spiders before you move in. use a drag to move mud up from the river. I have seen them made from mud and grass bricks mixed with some wood ash using a wood form. Either way you have to use a drag to pull up mud or dried bricks. this is good for a shelter that people need to be at for weeks at a time or regular intervals. they are fire proof and resist everything but floods an seasonal heavy rain.