What would cause this type of crack?

[gramps]

No apparant 'hit' just a bang and no chip or other external mark.

[screenman]

I have seen bird strikes cause that type of damage, but you said no apparent hit.

[usmc68]

I have the same type break about 3 1/2" in diameter. I was working under an oak tree and actually watched a squirrel drop an acorn on my windshield over 2 years ago. I left it alone and it has not spread at all.
This is probably the most rare type of break I have seen in 22 years.

[DryStar]

Any number of blunt objects could cause that (i.e. baseball, golf ball, baseball bat, larger stone with no edges,ect...) The hit mark would be the inner circle area. Just out of curiosity, how large is the damage?

[screenman]

By the looks of it that break is in both pieces of glass. The clue for me is in the centre what looks like a giant batswing, well behind this is a circle almost which is about the thickness of the glass away and overlapping.

[DryStar]

By the looks of it that break is in both pieces of glass. The clue for me is in the centre what looks like a giant batswing, well behind this is a circle almost which is about the thickness of the glass away and overlapping.

Screenman, what did you mean a giant "bats wing" or a giant "bat swing"?

[clearquest]

Large heavy but soft object that spreads the weight of the impact out over a larger area, rather than a small sharp impact. Impact was at the center part of the small rings,

[robert n]

Hey Gramps! Did you try to repair it...If so, how did it turn out?

[t4k]

Looks like the weather was conducive to a good repair too.

[DryStar]

I would guess, Gramps is taking a nab...and won't be on here anytime soon! Just got to love it when people post a question and never respond. Why...do we even bother???