Just a short walk or scooter ride from Hamilton City is a remote cliff-jumping point with a unique history, a history that extend further back than the arrival of the British Navy. Admiralty House was gifted to the British Royal Navy by the Bermuda Government back in the 1800s as part of the general defenses of the island. Today, what’s left of the historic home and building is now surrounded by a park, a hidden beach called Clarence Cove and Admiral’s Cave.
The buildings originally built for admirals who were stationed at the nearby dockyards, Admiralty House has had many lives, once serving as a Navy Hospital and as a signal center for the British Royal Navy during World War II. It was here that British officers would intercept coded messages from ships en route between the US and UK.
When Admiralty House was built back in the 1800s, a nearby manmade cave—now known as Admiral’s Cave—once housed British convicts. In fact, there are several underground tunnels connecting underground caves, that were constructed in the 1800s by the British military.
In 1951, Admiralty House was given back to the Bermuda government, abandoned and then eventually demolished. What is left are the remains of the once grand ballroom of this former naval outpost. By far, the biggest draw of Admiralty House today is its surrounding hiking trails, manmade caves, and cliff-jumping.
A rocky path to Admiral’s Cave reveals a stairway leading to the open ocean. Visitors will opt to either jump into the inviting cerulean water from the stairs or jump off of the overhanging cliffs.
This cave was named after a British Admiral Sir David Milne, wo completed his tour of duty on Bermuda around 1819. He had troops shipping speleothems home as a souvenir, among them a nearly 4 m high stalagmite. 44 years later the son of the Admiral, David Milne Home, visited the cave also. He saw, that a few millimeters of limestone had grown on the surface of the stump and extrapolated, that it would take 600,000 years to grow it to its former glory. This was in 1864 and was most likely the first time ever that the growth rate of speleothems was estimated.
The cave is one of the bigger ones and was once full of impressive speleothems. It also once housed the only dog-tooth spar crystals in Bermuda. But since the cave was abandoned as a show cave, a century ago, it was heavily damaged by vandalism.
Bermuda probably has more caves per square mile than anywhere else in the world. These caves are located in the older rocks close to the current sea level, and were formed during periods of low water levels during glaciation cycles of the current ice age. These cycles occur on 40,000 to 100,000-year time scales and we are now in an interglacial period following the end of the last ice age some 10,000 years ago.
As Bermuda emerged upward from the ocean during these interglacial periods, the downward drag of water in dunes and depressions found weak pockets of limestone between the lower rocks, and these were eventually flushed out. The lowering water level then allowed air into these newly formed caves, causing the formation of drip-rock and in time, the formation of stalagmites and stalactites.
Made of calcium carbonate, Spelothems grow as long as there is dripping water in an air-filled cave and become Stalagmites if growing from the floor and Stalactites if growing down from the ceiling. When they join, they become columns or pillars. Many caves that are now completely filled with water also contain Spelothems, indicating that they were once above sea level.
A major group of caves is located to the east of Harrington Sound, the largest being Crystal Cave. Admiral’s Cave, another large cave, is located between Blue Hole Hill and Grotto Bay and almost entirely above sea level. It is called Admiral’s Cave after Admiral Sir David Milne, who in 1819 removed a massive stalagmite from the cave and presented it to his friend Professor Robert Jameson of the University of Edinburgh for the College Museum.
The 1888 Bermuda Pocket Almanack contains the following report: “A splendid stalagmite cut from the Walsingham Caves is now in the Museum, Edinburgh, and has attached to it the following description: ‘Stalagmite of Carbonate of Lime Sawn from the Floor of a Cave in the Island of Bermuda’. The stalagmite was 11 feet 3 inches tall and weighed 3-1/2 tons.
In 1863 – 44 years after his father had removed the stalagmite – the Admiral’s son, Admiral Sir Alexander Milne, visited the cave where he had witnessed the removal as a boy, and found that 5 drips had formed small knobs of new matter on the stump of the stalagmite. He calculated that the new matter amounted to about 5 cubic inches and, as the stalagmite consisted of approximately 44 cubic feet – or 76,000 cubic inches – concluded that it would have taken 600,000 years to form the stalagmite that his father had removed from the cave. This calculation assumed that the deposits occurred at exactly the same rate as in the previous 44 years, something that is highly unlikely.
So the cave is the work or man and over 150 million years of Mother Nature via sea creatures, water pressure and time.
Bermuda Limestone, as its name suggests, is the particular type of limestone you see in the Admiral’s cave and all over Bermuda. This type of limestone was formed millions of years ago as the Bermudian islands themselves were created. Two distinct deposits of this material exist in Bermuda, and it has been quarried and used in Bermudian construction and as an important export commodity since at least the late 17th century.
Prior to its commoditized use as a building material or export product, Bermuda limestone traveled to Jamestown as ballast, likely in the hulls of the ships, the Deliverance and the Patience, the two ships reconstructed on Bermuda by the survivors of the Sea Venture shipwreck. The presence of Bermuda limestone in various archaeological contexts helps archaeologists date various features on the site, because it would not have been present in Virginia prior to May 1610, when the Deliverance and the Patience finally arrive at Jamestown.
Ballast is used to lower the center of gravity and provide stability to boats and ships. The stones would have been redistributed as goods were loaded or unloaded onto or off of ships coming and going from Jamestown in the early fort period. With many Bermuda limestone cobbles lying about and not very much brick being produced locally in 1611-1617, the stones previously used as ballast had a second life as construction material for the colonists. Large cobbles of Bermuda Limestone, along with other locally sourced river cobbles were found forming the foundations of the ca. 1611 Row Houses and the ca. 1617 addition to the Row Houses placed on the eastern end by Governor Argall. These foundations have been outlined on the site today, using some of the original cobbles that once made up the architectural structure found by archaeologists underground.
Famous Limestone Buildings around the Globe
Some of the world’s best-known and most-beloved structures were constructed from limestone. It was commonly used as an alternative to marble and granite in municipal buildings, bridges, colleges, and churches. The stone’s hardy nature has allowed many of these buildings to last for centuries.
Notable buildings made of limestone include:
- The Great Sphinx
- The Great Pyramid
- The Parthenon
- The Roman Colosseum
- The Empire State Building
- The Arc de Triomphe in Paris
- The Lincoln Memorial
- The Washington National Cathedral
- The Pentagon
- United States Holocaust Memorial
- The Biltmore Estate
- Chicago Art Museum
- Courthouses and Capitol buildings across the country
To log this earth cache, message or email us and copy and paste these questions, along with your answers. Please do not post the answers in your log, even if encrypted. There's no need to wait for confirmation from us before you log, but we will email you back if you include your email address in the message. Group answers are fine; just let us know who was with you.
1. The name of this earth cache: Admiral’s Cave – 150mil years in the making ABEC #4
2. Observe: Describe color of the limestone you see in the cave and surrounding area today. What, if any, evidence do you see of erosion from the water or other elements? Do you think limestone can resist weather well given what you observe?
3: Opinion, Based on your answer above and the lesson content. How long will the cave sustain? Given the chance will new spelothems grow as long as there is dripping water in an air-filled cave and become Stalagmites if growing from the floor and Stalactites if growing down from the ceiling? Can people help or hurt the process?
4. Send a photo of the cave with a new spelothem if you see one or the cave (only in the answer section) You can elect to be in the photo or not.
In the Log area
Send a picture of the lake or your favorite part of the cave. You are not required but you may be in the photos also to log this cache.
References
https://www.bermuda.com/know-bermudas-caves/
https://www.showcaves.com/english/bm/caves/Admirals.html
https://www.atlasobscura.com/places/admiralty-house-park
https://historicjamestowne.org/collections/artifacts/bermuda-limestone/