Permissions & Acknowledgements

Permission to publish this EarthCache trail has been granted by Great Yarmouth Borough Council following direct discussion with the council’s Property & Asset Management team.

No physical works are required for this EarthCache, and all locations are accessible from existing public routes. Many thanks to the council for their support in enabling this trail, which aims to encourage responsible exploration and engagement with the local geology and built environment.

🟢 GY Town Wall – Sediment Layers in Building Stone (Part 2)

EarthCache Type: Geological structures / building stone
Difficulty: 3.0
Terrain: 1.5

1. ✅ Logging Tasks (Stone A Only / B as Locator)

   Logging Tasks

   To log this EarthCache, please complete the following tasks at the posted coordinates and include your answers in your online log:

   Using Photo A, locate the stone block marked A.
   (The marker B is included only as an additional reference point to help you confirm you are looking at the correct section of wall.)

   1) Overall colour & surface
   Describe the overall colour and surface appearance of Stone A.
   (For example: smooth/rough, grainy, pitted, weathered, etc.)

   2) Bands / layers
   Look closely at Stone A.
   Can you see bands or layers that differ in colour, thickness, or texture?
   Describe at least one visible difference you observe.

   3) Direction of layering
   Observe the direction of the layers/bands in Stone A.
   Are they mostly horizontal, slightly angled, or uneven/irregular?

   4) Geological explanation
   Based on your observations, explain one geological reason why different layers within the same stone might look different.

   Optional:
   You may include either a photograph of yourself / an identifying item at GZ if you wish, but please ensure it does not reveal the answers.

🌍 Geological Lesson – Sediment Variation Within Stone

Although the Town Wall is a historic structure, this EarthCache focuses only on the geological features visible within the stone blocks, rather than on the wall’s construction or history.

Sedimentary rocks form when layers of sediment are deposited over time. These sediments are not always identical. Changes in:

• grain size

• sediment source

• water energy

• depositional conditions

can produce visible differences between layers, even within a single block of stone.

These layers (often called bedding or laminations) are geological records of changing conditions at the time the sediment was laid down. When the sediment later hardened into rock, those differences were preserved.

As a result, some layers may appear:

• slightly darker or lighter

• thicker or thinner

• smoother or more granular

By examining these visible layer differences in the wall stone, it is possible to observe sedimentary processes “frozen” in rock, using the wall as an accessible urban exposure.

Photo A – Observation Area

This EarthCache focuses on the wall section at the posted coordinates. The light-coloured dressed stone blocks can be observed safely from the public path.

If you can see the King Henry’s Tower plaque/signage shown below, you are at the correct location for this EarthCache.

Please examine the light-coloured stone block marked “A” in Photo A for the logging tasks.

⚠️ Important Notes

• The Town Wall is a Scheduled Monument.

• Please make visual observations only.

• Do not scratch, chip, or remove any material.

• Leave the site exactly as you found it.

📚 References

• British Geological Survey — Sedimentary rocks and structures

• British Geological Survey — Building stones of England

• Boggs, S. (2014). Principles of Sedimentology and Stratigraphy

🤖 AI Use Disclosure

Portions of the wording for this EarthCache were drafted with the assistance of an AI language model. The cache owner has personally visited this location, observed the geological features described, and reviewed and edited all content to ensure it accurately reflects the on-site geology and complies with EarthCache guidelines.