Providence City Hall floats on water - literally - ! Prior to the 19th century, most areas below the Rhode Island State House was a cove, known as "The Great Salt Cove" filled with salt marshes, wetlands, and boats that would traverse its waters. As downtown started to become developed, this cove started to get polluted. To mention a few pollutants, waste from the mills, waste from slaughterhouses upstream, and with no sewage system, the river served as a place to put human waste. At low tide, you can imagine how this smelled! The city eventually sold the cove to railroads in 1891. The work began then to fill it in to make the space usuable for railroad tracks. Providence created a man made Tidal Basin nearby at Waterplace Park which is a short walk away.
The cove area and downtown Providence are susceptible to flooding due to rising sea levels. Rhode Island in general, continues to sink, an estimated 4 inches per century. Subsidence is the gradual sinking in of an area of land, and can be due to many different factors. See photo below for a few examples of why this happens.
Flash forward to today! Providence City Hall was built on top of the Cove land. In order to build it, they needed to use 3,128 piles driven into the ground in order to have the building hold and be structurally sound. On top of the piles are large blocks of granite which form a "floating foundation" for the building. And more granite! The face of the building has granite on all four sides. Except, 2 of the sides has Westerly Granite, on Washington St and Dorrance St, and the remaining 2 sides have New Hampshire Granite, on Fulton St and Eddy St. Granite is a popular building material as it is sturdy, durable, and resistant to heat and frost.
There is no physical container at this location. You must read the cache page to learn more about what you will see and feel at GZ (Ground Zero). Please provide answers to the below questions in order to have a smiley face log remain.
1. Look around GZ. Based on what you have read and what you have observed at GZ, what factors are causing subsidence? Think carefully as there may be a few factors all contributing to this.
2. At the time of your visit, was there any flooding in the area?
3. Is there any notable difference in the New Hampshire Granite and the Westerly Granite? If so, what?
4. Describe the texture of the granite (smoothness, color, roughness, etc). Do you see any signs of failure or staining? If you do, what could be contributing factors?
5. Upload a photo of yourself, or your GPS, in front of the Providence City Hall