Verify the new geologic map that shows a third basalt layer in this area of Southbury, in contrast to older maps that only show two layers.  The basalt layers are a result of massive lava eruptions in this region 200 million years ago.

Collect data that will shed light on the hydrologic connection between the stratified drift aquifer and the deeper bedrock.

This work is in support of the scientific efforts of the Pomperaug River Watershed Coalition to better understand the water resources in the area.  Cornucopia at Oldfield is an avid supporter of the work of the Coalition.

Below is the initial summary of the drilling by the USGS:

PRELIMINARY RESULTS OF DRILLING AND LOGGING OF SOUTHBURY WELL
Bill Burton and Herb Pierce
 

Drilling of the monitoring well in the early Mesozoic Pomperaug basin in Southbury, CT has been completed (Cornucopia at Oldfield Bed and Breakfast, near intersection of routes 6 and 67).  The well was sited to confirm or deny the existence of a hanging-wall syncline of basalt and sedimentary rock in an area of poor exposure in the basin, as hypothesized on the new geologic map by Burton and others (2005 NEIGC), based on previous well records and structural interpretation.  The depth of the well is 410 ft, and depth to bedrock is 50 ft (casing set to 60 ft).  The flow rate as estimated by the driller was about 15 gal/min.  The sequence and thicknesses of lithologies encountered during drilling, based on sampling of well cuttings by Bill Burton and borehole geophysics by Herb Pierce, is as follows:  50-167 ft below land surface, basalt; 167-270 ft, red and gray siltstone and fine-grained sandstone; 270-410 ft, basalt.  Using the stratigraphy for the Pomperaug basin established by Huber, LeTourneau and McHone, the bottom 140 ft of basalt must be part of the Orenaug (“second”) basalt, the 103 ft of sedimentary rock above that must belong to the White Oaks formation, and the upper 117 ft of basalt must be part of the South Brook (“third”) basalt.  Acoustic televiewer images indicate that the contact of the Orenaug basalt with overlying, finely-bedded sedimentary rock of the White Oaks formation dips roughly south-southwest at about 15 degrees (uncorrected for magnetic declination and borehole deviation), while bedding dips in the sedimentary rock are near horizontal.   The sharp upper contact of the White Oaks formation with basal South Brook basalt dips roughly south at about 18 degrees.  The natural gamma log indicates that there may be an internal contact or transition in the White Oaks formation from red and gray siltstone (above) to predominantly gray siltstone (below) at about 218 ft. The EM flowmeter log indicates fluxes of ground water at depths of about 278 ft (basalt), 195 ft and 183 ft (sediment), and 166 ft and 88 ft (basalt).  Although many fractures were imaged by the televiewer, no major faults or fracture zones were seen.  More logging of the well is planned in the future, including optical televiewer and heat-pulse flowmeter.  Cuttings from the upper and lower basalts in the well will be analyzed for geochemistry.

The presence and orientation of South Brook basalt and underlying White Oaks sedimentary rock at the drill site is consistent with the interpretation of a hanging-wall syncline of these units in this area, about 3 km south of their only known exposures in South Brook.  The subhorizontal orientations are consistent with the position of the drill site near the axis of the syncline, as shown on the map.  The thickness of the South Brook basalt (minimum 117 ft) suggests that it must extend a certain distance farther south, before terminating at the nose of the syncline or along the eastern border fault.  The White Oaks formation is projected even further south based on reported possible excavations by Olsen and Huber of fine-grained sedimentary rock at the Southbury shopping center and a gravel quarry