In the end, to get from Potosí to Sucre I had to get a taxi, because buses were on strike indefinitely. I was sharing it with a traveller from the US, two Bolivian women, two babies and a dog, which made for a cramped journey. After about an hour and a half of good running on smooth roads through the mountains, our driver stopped to talk to someone, and got word that there was a roadblock of striking bus drivers ahead. We took to a side road to avoid it, and before long the side road became an axle-crunching bone-jarring mess of rock and gravel. Our driver was careful but the road was appalling. We bumped violently along it, occasionally hearing horrific grinding noises and once almost getting grounded on a large boulder, but after half an hour we suddenly rejoined the main road again, and arrived in Sucre about an hour after that, slightly bruised but happy to have made it.
Sucre was a great place - a striking colonial centre, a friendly vibe, nice bars and restaurants and lots to see. Having fallen in love with api in Potosí, I found another Bolivian treat here - buñuelos, a deep-fried doughy snack, which I ate in considerable quantities at an excellent cafe near where I was staying. Although we were still 2800m above sea level, it was much warmer here than it had been in Potosí, and so api was less important to my general well being.
The main thing I went to see in Sucre was a quarry. I'm not normally one to seek out heavy industry while travelling but the attraction here is a huge area of dinosaur footprints which were uncovered just a few years ago. An almost sheer rock face at the quarry was, millions of years ago, a flat muddy area, through which a whole bunch of dinosaurs walked. Their tracks criss-cross the rock face, and it's extremely impressive to see imprints left by many different types of foot, inconceivably long ago. But it's also slightly depressing that quarrying work continues, and even while I was there I could see trickles of dust coming off the rock face. Quarrying continues right up to the layer with the footprints on, and it's surely possible that the footprints won't be there for very much longer.
It was the 22nd of December when I saw the dinosaur footprints, and I fancied spending Christmas at Lake Titicaca. The bus strike, luckily, was coming to an end, and I bought a ticket to La Paz for the night of the 23rd. While Sucre is the constitutional capital of Bolivia, La Paz is a far bigger city and is the de facto capital. I was looking forward to seeing it. My bus left Sucre at about 6pm, and after a meal stop at about 7pm, we passed through Potosí at about 11pm. We stopped for a bit, and as the bus door opened a blast of freezing air whistled down the aisle. After that, I fell asleep - the bus was comfortable and had plenty of leg room. Early on Christmas Eve, I arrived in La Paz. I managed to get rapidly onto a bus heading for Copacabana, on the shores of Lake Titicaca, and we wound up the side of the valley that La Paz sits in, through the vast sprawl of El Alto on the valley edge, and then through populous farmlands to the lake.