Bradgate Park - The Swiss Roll

Instability in the rocks of Bradgate Park…

A rock outcrop with an oak tree growing out of it.

Five minutes walk to the east of Old John Town, you will find an area of woodland known as the Sliding Stone Wood. Next to this you will find a beautiful rocky outcrop, with an old oak tree growing out it. But this rocky outcrop has much more to offer than its good looks!

Take a careful look at its northern face and you will find that unlike the other rocks in the upper part of Bradgate Park, the layers of sedimentary rock are no longer all flat and parallel to each other. Indeed, the layers of sediment have been rolled up – giving the site its name, the Swiss Roll!

So how did this form? The layers of sediment were being deposited some time between 560 and 565 million years ago at the bottom of a deep sea. But they must have been unstable, either because of being on a submarine slope, or because of events such as earthquakes. Either way, soon after being deposited, but long enough after that the sediment had partially begun to stick together, the deposit was displaced and moved further down the submarine slope, mixing up the layers as it went. Look at how layers have rolled up – it tells us the sediment must have been ‘semi-lithified’ or partially turned to rock when the event happened, and the sediment likely had the consistency of plasticine. This type of deposit – one that has been redeposited downslope – is called a slump, and this particular unit is known as the Sliding Stone Slump Breccia.

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