Can the appearance of my bread offer any clues to what went wrong? I followed the Tartine recipe for basic country bread to the letter using a robust starter at its peak after feeding. The crumb is dense, there was almost no oven spring and no ear.
Thank you in advance.
I wouldn't call that crumb dense at all. A picture showing the overall loaf would help in assessing the rise, but the cross-section shows a good height. A good height and good pores without much expansion of the scores shows there was little rising potential left. This could mean something about the flour, or most likely that the loaf was proofed too long. It's also possible that your scores were too shallow and/or too vertical.
Don't forget, you are making bread with an uncontrolled mixture of yeast, bacteria, and flour. Following any recipe "to the letter" is not likely to be optimum for your bake with your starter and ingredients in your kitchen at your temperatures in your oven. The recipe, even if it's a good one from a reliable source (like Tartine), can only be a guide or starting point.
Personally, if I baked a loaf with that crumb and it tasted good, I'd be pretty happy and I would reduce the bulk or proof time (or both) a modest amount next time.
If you think you ought be have gotten large, irregular cavities, that's harder and has a lot to do with the shaping technique on top of all the other factors. Patience!
TomP
List this one in the win column.