This photo shows an automobile passing in front of a rock which is essentially fully exposed. The rock has a rough, dark surface indicating it is weathered basalt and is roughly circular in exposed cross-section. The rock is immediately adjacent to a roadway – the road cut removed much of the earth from one side of it exposing it – from the excavation it is evident that the rock sits on a mound of glacial till. The rock is approximately 2 times the length of the car (i.e., ~ 9 meters) in one direction and 5 times the height of the car in the other direction (i.e., ~ 9 meters). Since the rock has not tipped onto the road and no structural support is provided, it must be approximately as deep as it is wide and high. Since the density of basalt is 3 grams per cubic centimeter, this puts the mass of the rock at about 400 to 500 metric tons (consistent with the references).
{}