The first 500 million years or so . . . Part 3

270 Million YA Yucatan

We have wandered northwest to see this wonder. It was a difficult trip over very rugged terrain, but it’s worth it. We are standing on a fragment of Florida looking our at a huge rifting valley. On your left is the Yucatan Block. To the right is North America.

175 million years ago North America was being drawn away from the Yucatan Block. The resulting gorge made Death Valley look like a picnic area. Eventually this valley will flood to form the Gulf of Mexico. In the far distance is Texas and northern Mexico. Tucked in the corner between the Yucatan block and northern Mexico is a tiny hint of central America. Very little can live here. Delicate insects, which are carried in on the wind, last a matter of hours. There is a sand lizard which hunts mostly in the growing evening shadows.

Dinosaurs roam much of the landscape further toward the coast, but this is a very difficult place to make a living.

Alt Fracture Zone

Now we have come to the Late Jurassic/Cretaceous boundary. To the west (left) of us, lava oozes into the Proto-Caribbean Seaway. The water sizzles and roars. To the north (on the other side of the water) we see chunks which have been torn off of Africa. They will be shoved up against North America to form Florida. Just behind us, tropical forests are home to a variety of dinosaurs. Reptile-like birds catch insects and small rat-like creatures peep out from the shadows.

For millions upon millions of years rain will scour those distant hills. The ocean will pound against their shores. Slowly, those far away hills will disappear under the waves. The Florida plateau will slumber beneath the ancient tides.



Florida is truly a mysterious land. None of the deep geology belongs to North America. Florida is an add on.  At the center of the explosion which created today’s continents, it’s made  up of some of those continental fragments. Apparently there were five larger fragments. We can only guess at the shape and size of those pieces and where they fit in to the puzzle.

Ours is a very restless planet. There is a subduction zone along the southerly edge of Cuba creating one of the deepest local trenches. It’s caused by the Caribbean plate moving north. The entire end of the of the most southerly piece of Florida was broken off by the northerly movement of Cuba. That remnant now forms the Bahamas Islands.

Those distant formations are Moroccan shale. They will become some of the basement formations of our modern state.

Life itself provided much of the building blocks of the Florida we know. (Left) This is central Florida during much of the Cretaceous Period. Sea going reptiles hunted the shallow seas which were so rich in animal life.

It wasn’t the larger critters which helped build this state. It was the tiny ones. Using ocean chemicals like calcium and silica, the one celled animals built their skeletons. As they died, they drifted down to settle on the bottom. It was an endless rain of tiny skeletons. They mixed with sand and clays to form a variety of limestone, mudstone, and sandstone which make up the Florida plateau.


Early Jurassic

Next – Last Days: End of the Dinosaurs