Baleal Beach (Peninsula of Peniche)

Baleal Beach (Peninsula of Peniche)

by Nuno Correia, Porto, Portugal

The peninsula of Peniche presents a geological succession of sedimentary carbonate rocks strata of the Jurassic Age, a unique systematic register of 20 million years of Portuguese geological history.
The Lusitanian Basin, located on the western margin of the Iberian Peninsula, was formed during the opening of the North Atlantic Ocean, and the lithologies present resulted from rifting episodes alternating with periods of tectonic stability and consequent different subsidence. Their evolutionary history resulted in a nearly continuous sequence of the Jurassic period, resulting in an invaluable value known in the scientific community, but often unknown by the general public, or by the institutions responsible for ensuring the conservation of the natural values. As such, it is important to analyze the geological occurrences in order to show the potential that the Lusitanian Basin conceals, being these either educational, scientific, tourism, or others. In this dissertation, we made to the analysis of five sites in the west-central part of the basin, which all together, allow giving a brief insight into part of the evolution of the Lusitanian Basin during the Jurassic, including for this purpose field work and a more detailed analysis in some of those places using thin sections. The sites chosen were: a small hill where stands the windmill of the village of Dagorda (upper Triassic (Norian / Rhaetian) - Lower Jurassic (Hettangian / Sinemurian)); Cesareda Plateau (Lower Jurassic (Toarcian) - Upper Jurassic (Kimmeridgian); the Baleal peninsula (Middle Jurassic (Bajocian/Bathonian) - Upper Jurassic (Kimmeridgian); Consolation Beach (Upper Jurassic (Kimmeridgian); Paimogo Beach (Upper Jurassic (Kimmeridgian / Tithonian).