What's up with my radishes?

Hi All!
My indoor winter radishes are growing quite vigorously under a mix of grolux & daylight tubes, but the radish body appears to be forming above the (potting) soil surface, instead of below. Anybody know why this'd happen? Thanks!

 

Is it possible the soil has just settled?

 

hiya, MTB!

hadn't thought of that, but it doesn't seem so- looking closer, they are growing, but horizontally...

 

Is it possible their pots aren't deep enough? They may have hit bottom.

 

They're in a deep (dishwashers) tub, with 8" of soil beneath them. You hit on something I've wondered about... if there is a root depth chart of common veggies somewhere.

It might also be the Miracle Gro potting mix, I s'pose.