page_title: Bermuda
section_title: Geology
hierarchical_section_title: Bermuda / Geography / Geology
caption_attribution_description: English: NOAA Ocean Explorer Bermuda Geologic Map. where orange denotes the Walsingham Formation, purple denotes the Town Hill and Belmont Formations, green denotes the Rocky Bay and Southhampton Formations, and white is fill associated with the airport
context_page_description: Bermuda is a British Overseas Territory in the North Atlantic Ocean. It is approximately 1,035 km east-southeast of Cape Hatteras, North Carolina; 1,236 km south of Cape Sable Island, Nova Scotia; 1,759 km northeast of Cuba, and 1,538 km due north of the British Virgin Islands. Though it is typically referred to in the singular, Bermuda consists of 181 islands; the largest of these islands is known as Main Island. The capital city of Bermuda is Hamilton. Bermuda is internally self-governing, with its own constitution and cabinet of ministers selected from the elected Members of the lower house of a Parliament that enacts local laws. As the national government, the Government of the United Kingdom is ultimately responsible for ensuring good governance within British Overseas Territories, and retains responsibility for defence and foreign relations. As of July 2018, it has a population of 71,176, making it the most populous of the British overseas territories. Bermuda's largest economic sectors are offshore insurance, reinsurance, and tourism. Bermuda had one of the world's highest GDP per capita for most of the 20th century.
context_section_description: Bermuda consists of more than 150 limestone islands, but 5 main islands, along the southern margin of the Bermuda Platform, which is one of three topographic highs found on the Bermuda Pedestal. This Bermuda Pedestal sits atop the Bermuda Rise, a mid-basin swell surrounded by abyssal plains. Initial uplift of this rise occurred in the Middle to Late Eocene and concluded by the Late Oligocene, when it subsided below sea level. The volcanic rocks associated with this rise are tholeiitic lavas and intrusive lamprophyre sheets, which form a volcanic basement, on average, 50 metres (165') below the island carbonate surface.
  The limestones of Bermuda consist of biocalcarenites with minor conglomerates. The portion of Bermuda above sea level consists of rocks deposited by Aeolian processes. These eolianites are actually the type locality, and formed during interglaciations, and are laced by red paleosols, also referred to as geosols or terra rossas, indicative of Saharan atmospheric dust and forming during glacial stages. The stratigraphic column starts with the Walsingham Formation, overlain by the Castle Harbour Geosol, the Lower and Upper Town Hill Formations separated by the Harbour Road Geosol, the Ord Road Geosol, the Belmont Formation, the Shore Hills Geosol, the Rocky Bay Formation, and the Southampton Formation.
  The older eolianite ridges (Older Bermuda) are more rounded and subdued compared to the outer coastline (Younger Bermuda). Thus, post deposition morphology includes chemical erosion, with inshore water bodies demonstrating much of Bermuda is partially drowned Pleistocene karst. The Walsingham Formation is a clear example, constituting the cave district around Castle Harbour. The Upper Town Hill Formation forms the core of the Main Island, and prominent hills such as Town Hill, Knapton Hill, and St. David's Lighthouse, while the highest hills, Gibbs Hill Lighthouse, are due to the Southampton Formation.
  Bermuda has two major aquifers, the Langton Aquifer located within the Southampton, Rocky Bay and Belmont Formations, and the Brighton Aquifer located within the Town Hill Formation. Four freshwater lenses occur in Bermuda, with the Central Lens being the largest on Main Island, containing an area of 7.2 km² (1800 acres) and a thickness greater than 10 metres (30').
caption: NOAA Ocean Explorer Bermuda Geologic Map. where red denotes the Walsingham Formation, purple denotes the Town Hill and Belmont Formations, green denotes the Rocky Bay and Southampton Formations, and white is fill associated with the airport
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