Very interesting find. Whatever the explosive was that did the instant burial in the first place, it was big and effective.
On 12 June 1916 two companies of the 137th Infantry Regiment of the French army were sheltering in their tranchées (trenches), baïonnettes (bayonets) fixed, waiting for a ferocious artillery bombardment to end. It never did the incoming shells covered their positions with mud and debris, burying them alive. They werent found until three years later, when someone spotted several hundred bayonet tips sticking out of the ground. The victims were left where they died, their bayonets still poking through the soil.