split expanders

Archaeology or geology?

Hoary with age, these patterns look like fields separated by dry stone walls submitting to a rising ocean. They are however an entirely geological phenomenon called tessellated pavement, caused by the interaction between erosion and the joints that form naturally in rocks as they are slowly uncovered and the pressure from the disappeared overlying rocks releases. The lower rocks then expand and split, sometimes in amazing geometrical forms like these orthogonal joint patterns.

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Exploding trees

When trees are struck by lightning, usually a strip of bark is blown away, leaving a distinctive scar. However in some cases, particularly in older trees, the sap can boil in an instant. The gas created raises the pressure to such an extent that the tree literally explodes.

This is one reason why it’s unsafe to shelter beneath a tree in a lightning storm: aside from the risk of lightning “jumping” off the tree, an explosion can turn splinters of bark and wood into high-velocity projectiles.

Watch a video of a tree exploding after a lightning strike here.

Trees have also been known to explode during forest fires, or even in extreme cold: the water in the sap expands, splitting the bark with a sound described as being like a gunshot.