Nature Done Wright

The rocks on one side of the Clove — the ravine at High Mountain in nearby Franklin Lakes — are different from the ones on the other.

According to William Paterson University Geology Professor Martin Becker:

"On one side, elements of the rock are gabbroid. On the other side is traditional basalt. 

"The people who created the geological map for the NJ geological survey thought the rock was unique enough to give it a different identification.

"So it’s more coarse grain basalt than the western side.  There is a slight difference, and it has to do with the rate of cooling.

"The cooling history is based on depth of burial, so if something cools deeper in the earth, closer to the earth’s internal heat source, it takes longer for it to cool. And that’s going to result in larger mineral grains."

(Thanks, Professor Becker!)