If So Many People Died During the 40 Years of Wandering, Where are Their Graves?

If nearly the whole adult generation of Israel died during the forty years' wandering, why is not that whole region full of their graves (Numbers 14:34-35)?

Under the nomadic conditions of the wilderness journey, with a constant shifting from one site to another, there is no way that sturdy or well constructed graves could have been made as the adult generation passed away. Shallow burials beneath the surface of the sand or gravel would have failed to preserve any of the skeletons for a very long period, even though they might have escaped disturbance by carrion-eating wild animals (which is doubtful). No excavations conducted anywhere in the world have ever exhumed identifiable burials of this type, and in the nature of the case it would be very surprising if they did.

–Dictionary of Bible Difficulties