PENULTIMATE GEOLOGY IN OUTCROP
I can think of no better title to accompany this photo. Please imagine this as a 48 point banner headline.
A picture is worth a thousand words; an outcrop like this is worth, well, at least about 300 million years of geologic history. The ability to “read” the geologic history of an area by viewing its structures and stratigraphy is a skill essential to a geologist, and this spectacular outcrop is a virtual banner headline.
This outcrop is from Telherio Beach, Portugal. Geology addicts of all degrees of education can make out the awesome unconformity above the folded formation. Let’s add just a minimal of information: The lower deformed unit is upper Carboniferous in age (the Brejeira Formation) and the overlying undeformed unit is Triassic (the new red sandstones of the Grés de Silves Formation).
Before the deposition of the sandstone, the Brejeira Formation was 1. Deposited, 2. Deformed in some immense compressional event, 3. Exposed to weathering. The timing suggests that the folding is related to the merging of continental blocks into the Pangaean super-continent. The lack of deformation in the Triassic certainly suggests that at this locality anyway, not much has happened since.
Like all headlines, the details are given in the accompanying article. There’s so much more that can be learned by detailed study of these formations, their composition, their strain… but for a headline, this is one of the world’s penultimate geologic outcrops.
If this is the headline, I wanna read the whole story!
Annie R
Photo: Gabriela Bruno,Telheiro Beach, Portugal. And thanks to Francisco Sousa for inspiring this post.
Read also: http://rop.ineti.pt/rop/images/intro/it2_en.html http://revistas.ucm.es/index.php/JIGE/article/view/33912/0