Why has my bread done this?

Toast

I baked my first sour dough loaf today. It was delicious! However, it turned out strangely:



I had a bit of a disaster getting it into the oven, as I hadn’t floured the peel enough. By the time it went in, it resembled a pancake... it then rose relatively nicely, but obviously from the picture, it rose very unevenly. 

what did I do wrong to make this happen? I’ve had it before, but never to this degree. Is it a problem with how I’ve shaped it, or something else?

I'm just spit-balling here.  I'm sure someone with a little more experience can be of more help.  I would guess too much starter.  Along with what you describe as being difficult getting it in the oven.  It was a perfect storm for circus bread.