Cabbages splitting - help !

[roosky]

I have successfully - I thought - grown Golden Cross round-headed white cabbage, and we have been eating them for the last few weeks. They are big, about 2kg each on average. Now, in the last couple of weeks, they have started to split - they look as if they've just grown too big for themselves. We thought at first it might be wood pigeons, or even rabbits, although we're pretty sure they've been kept out. I put the net back over them, and took out the split ones, but they're still doing it. It looks as if a large animal had chomped its way across the top ! There are no obvious signs of slugs or beasties of any kind.
If it's not an animal or bird, could it be weather conditions ? We haven't had a wonderful summer up here, and there have been periods with lots of rain.
Any suggestions, anyone ?

[rustylady]

It's the weather. I would guess you've had a period of heavy rain recently. The cabbage heads were already mature and now with the extra water they've decided to grow a bit more and have split through the outside leaves.