I never got around to making my last vacation post. One of our stops was at the Submarine Force Museum in Groton, Connecticut. The centerpiece exhibit is the USS Nautilus (SSN-571), the world’s first nuclear-powered ship (commissioned in 1954).Unlike the Albacore, the Nautilus was a fully armed warship, but given its unique nature was mostly used for engineering and operational studies. It also laid the groundwork for much of the US Navy’s Arctic and oceanographic research that took place in the 1950’s and 1960’s. As the Nautilus’ nuclear reactors did not require air like conventional engines, essentially the only limit on its submerged time was the ability of the crew to function. With the need to surface for air removed, the Nautilus made several exploratory trips under the Arctic sea ice:
After the Nautilus demonstrated that the nuclear submarines could cruise under the Arctic Ocean, the US Navy began using submarines regularly under the sea ice, including surfacing through the ice to establish and resupply research camps on the sea ice.
Another exhibit at the museum is the X-1, a small experimental submarine:
The X-1 was commissioned in 1955, originally to help the Navy develop procedures for protecting harbors ffrom small submarines. It was also intended to test a hydrogen peroxide/diesel/battery propulsion system, that would allow the diesel engines to operate even without air to provide oxygen. In 1957 the X-1 was severely damaged when the hydrogen peroxide supply exploded. It was rebuilt with conventional engines, and starting in 1960 was used in the Chesapeake Bay to study various properties of sea water, including wave propagation and the interaction of light and water.
As we pulled into the museum another feature caught my eye; a rock exposure in the back of the parking lot:
Unfortunately I couldn’t get very close to these rocks, but they appeared to be metamorphosed sediments. A later check of the geologic map confirmed that this is an exposure of the Mamacoke Formation, which is indeed a gneiss thought to be derived from sediments. The age of the Mamacoke is controversial, but it’s thought to most likely be from the Late Proterozoic. Perhaps most interestingly, it’s an Avalonian rock. Avalon was a continental fragment that collided with Laurentia in the early Paleozoic, and Avalonian rocks pop up all over the New England and Canadian coasts. For example, Cambrian Saint John Group metasediments in Saint John, New Brunswick (the brown rocks on the left side of the image below):