Exploring the Jurassic at Zalas Quarry, southern Poland

Tomasz Borszcz and Dr Michał Zatoń (Poland) The area of southern Poland is well known for its widespread Jurassic deposits, in particular, Middle and Upper Jurassic sedimentary rocks that outcrop in a belt running from south-east to north-west in the area known as the Polish Jura Chain (Fig. 1). This area owes its name to the occurrence of spectacular klippes (outliers formed by thrusting) of by white, massive limestones deposited in the northern shelf of the Tethys Ocean during the Late Jurassic (Oxfordian). Because of their resistance to erosion, the rocks form a picturesque element in the surrounding upland landscape. Fig. 1. Location of Zalas Quarry against the background of the geological setting of the area. The oldest rocks in the area are represented by Carboniferous Mudstones (1) and conglomerates (3) and Permo-Carboniferous volcanic rocks (2 and 4). The Mesozoic deposits (5) are mostly covered by Cenozoic mudstones (6). In many places, the rocks are cut by faults (7) and rivers (8). As well as these, the Middle to Upper Jurassic deposits (in the form of glauconitic sandstones, marls, platy limestones and sponge-dominated reef-like structures called bioherms) occur in several natural and artificial exposures along the whole Polish Jura Chain. They are, and used to be, a real Mecca for professional researchers since the 19th century, and also amateur collectors from both Poland and elsewhere. This not surprising, as the deposits contain abundant and diverse fossils, including nearly all the fossil groups characteristic of this geological period. In this article, … Read More

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