That is a rudist reef far in the distance...the white looking bands on top of the mountain. During the warm Cretaceous period, when dinosaurs roamed the continents, reefs were dominated not by corals, but by oddly shaped mollusks called rudists. 
Rudists dominated the Earth’s shallow tropical seas, where they built massive reefs. Here German Geologist Wolfgang Stinnesbeck
points to a rudist fossil embedded in the rock at one of the canteras.
We had some very remote sites to go to and no hotels close by (or anyone for that matter) so we camped...I was in heaven of course! This site was in a riverbed that, had it rained we would have been washed away, but it was definently the dry season as there was at least 2 inches of fine dust on the surface. At least you didn't have to fuss with sleeping on rocks. So we made camp and as you can see we were camping in style. We all went shopping together 
before heading to the desert. The Germans only bought meat and beer! and lots of it!... 
but since 2 of us were vegetarians, we had bought some nice veggies and had great guacamole every night. It was nice to see everyone pitch in and help prepare dinner. We all got to know each other a little bit better around the campfire!
And it wasn't all work!
We stopped in Monclova, Mexico to check on an exhibition that Javier helped produce. This exhibition shows many of the dinosaur fossils that were found in the state of Coahuila. They also have created an animated display 
of what they were like! These dinosaurs lived here over 70 million years ago. 
Just a few road shots as we travel north....this is an apple orchard that is protected from hail storms with netting. It goes for miles!
This is Pico Orizaba in the distance, the tallest peak in Mexico at 5,636 meters (18,490 feet). This volcano is dormant but not extinct, with the last eruption in 1687. It is snow covered yearround. 
Beautiful desert with the Sierra del Carmen mountain range.
Camping on the edge of a prehistoric reef and what used to be a deep ocean, but now is a desert. Many finds await us. 
Fossiled shark vertabrae.
Examining a piece of sediment with a geologic loupe (magnifying glass) that contains a prehistoric fish tooth.
That's a little close there girls..HA! 
This arch at the entrance is home to thousands of bats (los murcielagos) that we saw pour out of a crevice right at dusk, just in time for them to eat the mosquitoes!
They have built very sturdy stairs to go down to these, 
unlike the rickety ladders in some. The fresh, clear water is rejuvenating to the body and mind! Here is the view from the bottom of the spiral stairs looking up. This one has artificial lighting as it is so far down. I suppose the Mayans used torches to see down here?
Working our way home....here at Cobá...where you can still climb the tallest pyramid in the Yucatan Peninsula...it is quite a climb and today it was very very windy.
The view is spectacular and we were trying to figure out how far away was the horizon?.....as geographers we thought we should know that...so googled it when we got home and the answer is not so simple....complex formulas take into account the curvature of the earth and refraction of light and so on..but for all practical purposes the formula is this.... SquareRoot(height of eye above surface in feet / 0.5736) = distance to horizon in miles.....so we will use the height of the pyramid as we were on the top....SquareRoot(137 feet/ 0.5736) = 15.45 miles to the horizon. Or for yall in the metric world it is
Of course I was not thinking of that on my descent...more concerned about keeping my skirt down.
Now the truks are used for transporting tourists to 3 cenotes. The small horses pulled us along by the local men holding on to the ropes.
The cold underground cenotes were well worth the long bumpy ride to get there. Somehow our timing was impecible to stay ahead of the crowd of tourists that have discovered this place. Most of the time we had them to ourselves! 
As honey is one of the main export crops of the Yucatan, we were always looking for local honey (miel)and so upon asking a women cooking chicken on the side of the road where was the mielero, she pointed to a man walking down the road in a white hat. We turned the car around and followed him to his house where he very graciously served up the honey in any empty water bottle we could find in our car(makes for excellent souvenirs to take home). It was delicious! 
He was very proud to show us his cyntrifigal force extractor that he made himself. As fellow beekeepers we were somewhat familiar with the
This cave system is amazing! There are some indications of very early human occupation! Along with 10,000 year old Mammoth bones, human made tools were discovered.
The cave has been left almost intact, with no pedestrian walkways just the natural bumpy floor of the cave. 
There were wall carvings, paintings and other artifacts besides the immense natural beauty of the cave. Some of the columns of joining stalactites and stalagmites would produce sounds with different tones when knocked.
Very nice geometric designs here!
