By Dan May
On Our Land
Dan May
The place name “Stony Creek” in the minds of many here is apt to be followed by the words “brewery,” “urgent care center,” “beach” or maybe even “quarry.”
For a handful of us, though – mainly architects, landscape designers, masons, and geologists – the completed phrase would be “Stony Creek granite.”
This granite has been mined at a Branford quarry since 1858 and is one of Connecticut’s more famous and recognizable rocks. The pinkish red to reddish orange color of the Stony Creek granite distinguishes it from the more common grey granites from Vermont and Rhode Island. From regionally prominent displays such as the pedestal for the Statue of Liberty to paver stones at Grand Central terminal and Bryant Park, it can also be found in cityscapes and building facades from Boston to Washington, DC, as well as many other US cities. It has even been exported to Germany and Australia.
I first noticed this building stone when I started working at the University of New Haven. It makes up the exterior stairs for the buildings that once comprised the New Haven county orphanage and foster home, and which ultimately became part of the campus. These buildings date from the early 1900s and today are known as Maxcy Hall and The Gatehouse. The stairs are generally in better shape than concrete stairways constructed in recent decades for newer campus buildings.
Stony Creek granite is very durable and resistant to weathering, including from salt used for deicing. Hence its use for walkways, curbs and exterior staircases. The small rocky granite outcrops that make up the Thimble Islands of Branford are also testament to the natural durability of this rock and its resistance to erosion, even from waves. Large quarried blocks are used for shoreline protection, breakwaters and groins along the central Connecticut shoreline.
The granite does break down over time, however, and the large grains that make up this rock yield a light-colored sand and gravel. It’s these bits of sand and gravel that inspired the name for Stony Creek, which drains the watershed where the granite occurs.
The sand at Stony Creek Beach is also noticeably different in color and texture from that of Milford’s Silver Sands Beach, which is derived from local metamorphic rocks rich in a glittery mineral called mica.
An occupational byproduct of working as a geologist is an inclination to identify distinctive building stones, but it’s also a useful guide to regional geology. Historic buildings in particular were often decorated with locally available stone, as the costs of transporting large quantities of rock any distance were prohibitive.
As an example, the cornerstones, windowsills, and decorative entrance facades of Maxcy Hall and The Gatehouse are all a white marble – almost certainly from western Connecticut and from a rock formation known as the Stockbridge marble. Other 19th and early 20th century buildings with ornamental accents of white building stone in our region were similarly sourced.
Mable is a comparatively soft rock, easily cut or sculpted, but also prone to rapid weathering and partial dissolution from rain. The marble shows this aging, and cemetery headstones inscribed in marble from a century ago are now nearly illegible. For a geologist, though, the origins of the Stony Creek granite and Stockbridge marble also point to the juxtaposition of two very different geologic terranes during an era of mountain building that formed the crust of central Connecticut hundreds of millions of years ago.
Modern buildings often incorporate more imported stone. It can be enjoyable for a geologist to think forensically and work out their origin. The ubiquitous bluestone pavers common to the area are most often from slate beds in New York or Pennsylvania, and the thin sandstone blocks fronting Valley Diner in Derby or Panera Bread in Milford are likely from the American Southwest.
Be careful, though, about inviting a geologist to your home, as they are more apt to be studying your granite countertop than the food on your plates.
Dan May is a geologist and professor of environmental science at the University of New Haven. He can be contacted at dmay@newhaven.edu.