Why is my sandwich loaf splitting?: I followed the one stage sourdough recipe I found on this site.  I used freshly ground whole wheat only.  I also followed JMonkey's shaping video. Well I probably made some errors since I don't know yet why and how the loaf is optimized. SO what happened? Why did it split so much?

Also why could i only slice it quite thick?  Could it have been too freshly out of the oven? 

Here is a picture of the slice;

loaf slices