Toward this goal, we present the results of detailed structural mapping and fabric analysis of trilobite-bearing Middle Cambrian
rocks in Beavertail State Park and along the western coastline between Beavertail and Fort Getty state parks in Rhode Island (Fig.
In both areas, trilobite biostratigraphy identifies a late Early Cambrian (Bonnia-Olenellus Zone) to Middle Cambrian
(Glossopleura Zone) depositional age for the Mount Cap Formation.
Most of these animals just seemed to disappear at the end of the Middle Cambrian
The Middle Cambrian
aquifer is sealed by a thick (500-900 m) shaly package of Ordovician-Silurian age representing a reliable seal rock.
Australian Middle Cambrian
molluscs and their bearing on early molluscan evolution.
They view the Late Ordovician Hirnantian glaciation as the most pronounced expression of episodic cooling of any event between the Middle Cambrian
and Late Silurian, and propose that it may have been orbitally controlled.
quartzose sedimentary strata in the Pocologan River area to Middle Cambrian
rocks in the St.
The well-preserved remains of more than 100 species of arthropods (invertebrates such as insects, scorpions and millipedes), sponges and other creatures, embedded in the Burgess shale since the Middle Cambrian
530 million years ago, provided scientists with a distinctly rare glimpse of life near its very beginnings.
The black shales forming the detached, imbricated allochthonous blocks can be subdivided into those belonging to the Middle Cambrian
and Upper Cambrian, with the highest grades of mineralisation occurring in the Upper Cambrian black shales.
In the east-neighboring area near St Petersburg, east Russia, similar age spectra of detrital zircon were lately reported from the Middle Cambrian
, Ordovician and Devonian (but not Lower Cambrian and Ediacaran) sandstones (Kuznetsov et al.
The goal of these studies was to test an established tectonic model, and help separate out the effects of late Cambrian and Devonian deformation, which mask the short-lived middle Cambrian
extensional event associated with VMS deposit formation.
The Wisconsin find is important because it partially fills the gap between two previous major discoveries of fossilized soft animals: one dating from the middle Cambrian
(about 530 million years ago) and the other from the Lower Devonian (about 400 million years ago).