It is as scary as it sounds. Well foliated limbs or entire trees really do fall spontaneously during the calmest of warm weather. It never fails to frighten anyone who witnesses it. Those who witness it always express the same difficulty with trying to explain it to those who did not witness it, as if they know that no one will believe them.

Several people heard this cottonwood limb fall onto a bridle path in Felton Covered Bridge Park. It is not a particularly large limb. The diameter about a foot above the flared union is only about seven inches.

Yet, even this relatively small limb is seriously dangerous when it falls from above, and from such a height.

A much larger sycamore limb that was almost two feet in diameter fell nearby a few years ago. It was like a full sized tree falling from the sky!

What makes…