Castle Down facts for kids

Castle Down is a wild, open area on the northern part of Tresco island in the Isles of Scilly. It's a special place because of its unique plants and rocks. It's known as a Site of Special Scientific Interest (SSSI). This means it's protected for its important nature.

Castle Down is also part of the beautiful Isles of Scilly Area of Outstanding Natural Beauty. It's also a Heritage Coast and an Important Plant Area. This shows how important it is for both its scenery and its plants.

You can find many old structures here, from ancient burial mounds (called cairns) from the Bronze Age to castles from the 1500s and 1600s. These castles were built to protect the nearby New Grimsby harbour.

A Look Back in Time

People have lived on Castle Down for a very long time. There are 66 cairns here. These are stone mounds, usually built as burial places, and they date back to the Bronze Age. That's thousands of years ago!

Just south of Castle Down, you can see signs of an Iron Age farm. This includes old field systems and hut circles, which were where people lived. There are also large middens, which are like ancient rubbish heaps. These huts were about 5 to 7 meters wide. The middens were up to 11 meters long and 1 meter high.

Old Castles and Forts

On the west side of Chapel Down, you'll find King Charles's Castle. This fort was built between 1548 and 1554. It was meant to guard the deep water entrance to New Grimsby harbour. However, it wasn't built in the best spot. It was hard to shoot at ships below, and it wasn't strong against attacks from the land.

For a short time, this was the main fort on the islands. But in the 1590s, Star Castle on St Mary's island became more important. King Charles's Castle was later used as a quarry. Its stones were taken to build the nearby Cromwell's Castle.

King Charles's Castle got its name because Royalist soldiers used it during the English Civil War. In 1651, Parliamentarian forces took Tresco. Later that year, Admiral Robert Blake captured the islands from the Royalists.

Right after this, Cromwell's Castle was finished in 1652. It was built on the site of an older fort. This round tower was also built to protect the harbour. It was updated around 1740 with a platform for cannons.

Piper's Hole Cave

Piper’s Hole is a deep cave on the north coast. You have to climb down the cliff to reach it. The cave has a 20-meter long passage filled with rocks. This leads to an underground pool. In the 1800s, when tourism started, a small boat called a punt was kept here. Tourists would use it to explore the inner part of the cave.

The Land and Its Features

Castle Down is the northern part of Tresco island. It's a plateau, which is a flat area of high ground, about 35 meters high. The ground is made of a type of rock called granite.

About 18,000 years ago, a huge ice sheet probably reached the northern Isles of Scilly. You can still see signs of this. There are erratic pebbles on the downs. These are rocks that were carried by the glacier and dropped far from where they came from.

You can also see raised beach deposits on the cliffs. These are old beach materials that are now higher than the current sea level. The soil on Castle Down is thin and sandy. The area is also very windy, with lots of salt in the air from the sea.

These tough conditions mean that the plants here grow low to the ground. They form a "waved" maritime heath. This heath is full of lichens and is mostly covered by heather.

Plants and Animals

The northern part of Tresco is a Site of Special Scientific Interest (SSSI). It's special because of its unique "waved" maritime heath, its many types of lichens, and a group of Common Tern birds that nest here. It's also important for its geology (the study of rocks and landforms). The SSSI was first protected in 1971.

Plants of Castle Down

Because the soil is thin and the winds are strong and salty, the plants here grow very low. They form a carpet of heather that's only ankle-high. "Waved heath" gets its name because the plants look like waves. On the side facing the wind, the ground is bare. But on the sheltered side, the leaves and flowers are thick.

There aren't many different types of plants here. You'll find western gorse and some bell heather. Bell heather grows more on the southern side of the area. Other plants include common bird’s-foot trefoil, English stonecrop, heath bedstraw, lousewort, and tormentil.

Scientists have found 45 different kinds of lichen here. Some are very rare. For example, the only places in Europe where you can find Heterodermia propagulifera are in the Isles of Scilly!

Animals of Castle Down

In 1993, scientists explored Piper’s Hole cave. They found a tiny creature called a springtail that had never been seen in Britain before. Its scientific name is Onychiurus argus. This type of springtail is known to live in caves in other countries like Belgium, France, and Spain.