Usually used on more long term shelters but cob is about like wattle and dab on steroids. It's a mixture of clay, straw, and sand. Mixing grasses and sand in with the clay makes it hold together a lot better. People build homes with it usually very thick walls that may or may not be load bearing. Helps to have it on a stem wall with a good overhanging roof to keep the rain from washing it away. Would be good material for filling the gaps in the walls if you want something more durable than simply clay or mud. A good overhanging roof and a stem wall of rocks about a foot high would increase it's durability many times over. There are thatch roofed buildings in europe built in this manner that have been around for more than 500 years.
You could even make yourself a little fireplace in it with cob. Look up the ratios used for making wood fired pizza ovens out of it. Some cob and rocks built into a little hearth and chimney. The more mass you put into it the better. Fire warms the cob and rocks, radiates warmth long after the fire is gone. Might be a little overkill for this project, but it's a neat material to know how to work with in the sense of long term survival. It can make anything from a pizza oven to a home, and most of the materials for it are probably already available to you near the site.
