CORRELATION OF EAST BERLIN (EARLY JURASSIC) VAN HOUTEN CYCLES TEMPORARILY EXPOSED DURING CONSTRUCTION IN ROCKY HILL, CONNECTICUT: A CONUNDRUM

Recent mapping at construction sites adjacent to Dinosaur State Park within the Mesozoic Hartford Basin revealed three Van Houten cycles in the Early Jurassic East Berlin Formation that are difficult to correlate with the type section in Berlin, 8 km to the west. A Van Houten cycle consists of the sediments deposited during the filling (transgression) of a lake, black shale deposited during the lake high-stand, and sediments deposited during the evaporative draining (regression) of the lake along with subsequent playa and alluvial plain sediments deposited on the former lake beds. The cycles at the construction sites may correlate to three of the type-section cycles but they are made up of slightly different facies. This may be explained by detrital input due to the closeness (less than 4 km) of the area to the Eastern Border Fault (EBF) and the source area for the basin detritus. Alternatively, these may be part of three older, previously unrecognized, Van Houten cycles.

The cycles in the temporary exposures are thicker than any at the type section, they are coarser-grained (including conglomerate beds), and they contain few of the distinctive features found in cycles at the type section. The deep water facies of each of the Van Houten cycles at the construction sites, however, is thinner than might be expected according to the generally accepted thickness vs, distance from EBF relation proposed by LeTourneau. Fossil footprints were recovered from various layers associated with each Van Houten cycle. Fish fossils, however, were not found.