AN EXPLORATION OF THE OCCURRENCE AND PRESERVATION OF EUBRONTES, THE STATE FOSSIL, WITHIN JURASSIC EAST BERLIN FORMATION LACUSTRINE CYCLES - CONNECTICUT GEOLOGICAL AND NATURAL HISTORY SURVEY (CGNHS) MAPPING DURING ACTIVE EXCAVATION

In August 2006, construction at the Veterans' Home in Rocky Hill, CT uncovered dinosaur tracks (Eubrontes and Grallator) in the Jurassic East Berlin Formation. The Connecticut Department of Public Works called CGNHS and specialized geoscientists to evaluate the find. Several of the individual tracks were well preserved, but most were poorly preserved, having one or more toes blurred by processes subsequent to the impression making. The judgment of the geoscientists was not to further delay construction in exploration for additional specimens. The discovery generated renewed interest in the paleontological resources of the area, near Dinosaur State Park, and debate in the media regarding destruction of a potential track site.

Because excavation is also planned for an adjacent property, detailed geologic mapping was recommended to evaluate the potential for uncovering additional tracks during continued excavation. In response, CGNHS has undertaken daily monitoring of the construction site at the Veterans' Home. The Survey is compiling a detailed geologic map to document the depositional environments of the Jurassic sediments as they relate to the occurrence of fossils. The geologic map will be used for future geotechnical planning and to predict areas where excavation techniques can be employed to recover additional specimens for scientific purposes.

The site stratigraphy consists of alternating reddish-brown playa-lake sediments with gray and dark gray perennial lake sediments. Cycles are ~20-25m thick. Most of the dinosaur tracks have been recovered from beach facies of perennial lake cycles. Poorly preserved tracks have also been recovered from playa lake facies. Several prominent conglomerates occur in the section. The site is on the south flank of the Rocky Hill Anticline. Several high-angle faults with minor displacements occur. A major fault (inferred), oriented ~070^o, with an apparent displacement of 70-80m, crosses the site.

Projecting the map westward from the construction site suggests potential track layers will be encountered on the adjacent property. Continued geologic mapping during the current and future state project will be part of the environmental planning as a proactive measure to conserve paleontological resources. Recovered tracks will be used in public educational displays.