555 Roosevelt Ave
Geology
Let’s take a look underground!
Rhode Island is the only state in New England formed entirely atop basement rock from the microcontinent Avalonia. The bedrock of Rhode Island first took shape with the emergence of a chain of volcanoes near the place where Avalonia collided with the supercontinent Gondwana. The earliest rocks likely formed in the late Neoproterozoic period, about 600 million years ago.
The geology of the RestoredWaters RI project is considered to be the Rhode Island Formation. A geological formation is a body of rock having a consistent set of physical characteristics. The Rhode Island Formation is the thickest and most extensive formation in Narragansett Basin. It consists of gray sandstone and siltstone and lesser amounts of gray to black shale, gray conglomerate, and coal beds.
What are we building here?
A gate and screening structure and drop-shaft site to direct CSO flow from the Upper Blackstone Valley Interceptor to the tunnel. Then the water will go to the Bucklin Point Wastewater Treatment Facility for cleaning.
What’s underground?
Depth to bedrock: 30-40 feet
What’s the rock? Mostly sandstone with small amounts of conglomerate sandstone and siltstone
- Sandstone is a classic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Rock formations primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers.
- Siltstone is a classic sedimentary rock composed mostly of silt. Siltstones differ from sandstones due to their smaller pores and a higher propensity for containing a significant clay fraction. Although often mistaken for a shale, siltstone lacks the tendency of shale to split along flat parallel planes of weakness. Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes.
- Conglomerate is a clastic sedimentary rock made up of rounded rock fragments that are greater than two millimeters in diameter. The spaces between the fragments are generally filled with sand- and clay-size particles. The rock is bound together by a cement that is usually composed of calcite or quartz.
- Sedimentary rocks are one of three main types of rocks, along with igneous and metamorphic. They are formed on or near the Earth’s surface from the compression of ocean sediments, pre-existing rocks or pieces of once-living organisms. Sedimentary rocks often have distinctive layering or bedding.