27 June 2012

Manganese Nodules and Phosphate Crusts

In the Lower Carboniferous age section here we see a potential buried manganese-phosphate
crust layer. Sedimentation rates see definitely low in this section.
Unfortunately it is behind a Prohibito sign and we had to leave before
we had time for a thorough look.


Lots of plants and bones in this conglomerete. Pictured is a small bone, potentially an amphibian or early reptiles scapula?

Angular Unconformity

Big Calcite Crystals

We find massive calcite crystals in fractures throughout this part of
the Devonian section. These calcites are cloudy, so they most likely
formed in higher temperatures; lots of two-phase fluid inclusions

Karst Caves

In a lot of the Devonian around here we see karst caves.


A grainstone with Lots of crinoids here, so an enchronite.


Fabric indies coral in growth position. A lot of them here, as well as
other indicators, so beds are overturned.


More reefal Devonian here. Lots of tabulate and solitary corals.

Another Red Sandstone

This red sandstone is the San Pedro or old Red Sandstone from the Devonian.


Silurian lutite, with graptolites in some areas, but not here.

Early Cave Art



Older to younger, now back to older -- thrust fault! [Here comes the rain...]

Upsection or Downsection?

We're hiking up and the beds are steeply dipping, and we end up in a
Dolomite. Overturned? What should be next?


Our first close up look at one of the red sandstones, the Lancara. We
see a lot of brachipods and echinoderms here.


Lots of Carboniferous coal basins in this part of Spain.

Sheep Dogs

Lots of flocks of sheep are left to wander around this wonderful
geology unattended, but for a few dogs to watch after each group.

Day 10

Overview of the Cambrian thru Carboniferous in this area, and
comparison to similar rocks we have seen elsewhere. For instance, the
three reddish beds one can use as markers throughout most of the area;
Lancra, San Pedro (equivalent to the Old Red Sandstone), and Riot.
Also, when we see gorse -- in bloom with yellow flowers at this time
of year -- we are looking at the sandstones.