World's Only Moving Mud Puddle

So, it moves thru very heavy things easily. The gas is mixing with the soil and severely lowering its internal viscosity. Like the Leidenfrost effect, but at room temperature. The long metal bulwark won't work because as compared to the gas, it has a huge difference in density. Metal also transfers heat extremely well, so it could easily transfer the heat from one side of the bulwark to the other side, heating the sand, and continuing the movement of the mud puddle. Also, how deep is the gas bubbling up from? The puddle seems to meet obstacles by seeing how rigid it is, meeting some resistance, and then off-shooting to avoid the rigid thing. Think of simple vector mechanics here. Picture an isosceles triangle sunken into the ground with its tallest side pointing downwards. Imagine yourself along the two sides facing downwards at various points. At the apex of these two sides is where the hardest ability to move straight-up will be. Along the sides will be theSince the puddle seems to be moving along in a line, it seems this line, of whatever it is, is helping to direct the puddle forward. So, my proposal for fixing this is to create a lower density at the top, so that it wants to find relief only in this less dense spot and so remains there. The gases are noxious and may be flammable. So, when the spot is remained fixed, a building could be built around the spot and the gases collected to either move a fan for energy production, or the gases burned for combustion energy production.