It's pretty gnarly, but she's going to be okay. The worst of it is that she wouldn't let them clean it at first aid, so after trying a good while to talk her into it, they finally just put ointment on a big bandage and slapped it over the whole bloody mess. She soaked it off in the tub that night and I picked out little rock bits with tweezers before applying a fresh bandage with ointment.
She says she enjoyed the zoo even though she hurt her knee.