Foundation Geology

To turn your learning into a real-world experience, here are ten practical activities you can undertake along the Sidmouth coastline. These activities range from simple observations to "citizen science" experiments.

1. The "Colour Gradient" Hike

Walk from the Western Town Beach toward Ladram Bay.

• The Activity: Track the shift in color. Notice where the deep "Rust Red" of the Triassic Mudstone meets the "Yellow-Green" of the Upper Greensand capping the hills.

• The Learning: This helps you visualise the timeline between the ancient desert and the later marine world.

2. Spot the "Great Unconformity"

Stand at the start of the South West Coast Path on Peak Hill and look back toward Salcombe Hill.

• The Activity: Try to find the sharp horizontal line where the red rock stops and the lighter rock begins.

• The Learning: You are looking at a "missing" 140 million years. Photograph it and draw a line on your photo to show where the Jurassic Period should have been.

3. The Pebble Provenance Test

Pick up a handful of shingle from the beach near the mouth of the River Sid.

• The Activity: Sort the pebbles into "Local" (red/sandstone) and "Exotic" (flint, white quartz, or dark limestone).

• The Learning: If you find flint or quartz, they have traveled from further east or were dropped by ancient glaciers, demonstrating how the ocean moves material.

4. Search for "Reduction Spots"

Examine fallen blocks of Sidmouth Mudstone (staying at a safe distance from the cliff face).

• The Activity: Look for small, circular green or grey spots within the red rock.

• The Learning: These are "reduction patches" where organic matter or a lack of oxygen turned the red iron oxide into a different chemical form.

5. The Permeability "Weep" Hunt

After a period of rain, look up at the cliffs where the Upper Greensand sits on the Mudstone.

• The Activity: Look for "weeping" lines—areas where water is literally leaking out of the cliff face halfway up.

• The Learning: This identifies the slip plane. You are seeing exactly why these cliffs are prone to landslides.

6. Fossil Detective: The Micro-Hunt

The Otter Sandstone (to the West) is better for large fossils, but the Upper Greensand (to the East) is great for small marine life.

• The Activity: Use a magnifying glass to look at fallen chunks of light-colored sandy rock. Look for tiny spiral shapes or shell fragments.

• The Learning: These are the remains of creatures that lived in the shallow Cretaceous sea.

7. Texture Comparison: Breccia vs. Sandstone

Find a piece of Breccia (angular fragments) and a piece of Sandstone (smooth grains).

• The Activity: Rub your thumb over both.

• The Learning: The sharp edges of the Breccia tell you it was formed by a violent, fast event (like a landslide), whereas the fine Sandstone suggests a steadier environment (like a riverbed).

8. Measure the "Blocky Weathering"

Look at how the Sidmouth Mudstone falls away.

• The Activity: Observe the "cubes" or blocks of mudstone on the beach. Use a ruler to measure the average size of these fallen blocks.

• The Learning: This is called "blocky weathering" and is a unique characteristic of mudstone compared to the way sandstone erodes.

9. The "Crystal Quest" (Gypsum Hunting)

Look for thin, white, fibrous veins running through the red mudstone.

• The Activity: Try to scratch a white vein with your fingernail. If it scratches easily, it is likely Gypsum.

• The Learning: This mineral is a 2 on the Mohs scale (very soft) and proves the area was once a drying salt lake.

10. Map the "Braided Rivers"

Look at the Otter Sandstone layers at the western end of the beach.

• The Activity: Look for "cross-bedding"—diagonal lines within the horizontal layers of rock. Sketch the direction these diagonal lines are pointing.

• The Learning: You are mapping the direction of an ancient river current from 240 million years ago!

Safety Reminder: Always check the tide times before heading onto the beach and never stand within a "cliff height" distance of the base of the cliffs, as rockfalls in Sidmouth are frequent and unpredictable.