Geology for ELR NAB is based on British Geological Survey (BGS) low-resolution data sampled at 100 metre intervals along the ELR. The geology presented should not be treated as accurate or complete. Data marked with Ⓤ is classed as undifferentiated by the BGS.
| Mileage | Material | Deposit | Bedrock |
|---|---|---|---|
| 0M -003y to 2M 0935y | South Wales Upper Coal Measures Formation - Mudstone, Siltstone, Sandstone, Coal, Ironstone and Ferricrete | ||
| 2M 0935y to 4M 0165y | Clay, Silt and Sand | Alluvium | South Wales Upper Coal Measures Formation - Mudstone, Siltstone, Sandstone, Coal, Ironstone and Ferricrete |
| 4M 0165y to 5M 0605y | South Wales Upper Coal Measures Formation - Mudstone, Siltstone, Sandstone, Coal, Ironstone and Ferricrete | ||
| 5M 0605y to 5M 1265y | Diamicton | Till | South Wales Upper Coal Measures Formation - Mudstone, Siltstone, Sandstone, Coal, Ironstone and Ferricrete |
| 5M 1265y to 6M 0935y | South Wales Upper Coal Measures Formation - Mudstone, Siltstone, Sandstone, Coal, Ironstone and Ferricrete | ||
| 6M 0935y to 6M 1265y | Diamicton | Till | South Wales Upper Coal Measures Formation - Mudstone, Siltstone, Sandstone, Coal, Ironstone and Ferricrete |
| 6M 1265y to 7M 0715y | Diamicton | Till | Pennine Middle Coal Measures Formation and South Wales Middle Coal Measures Formation Ⓤ |
| 7M 0715y to 7M 1705y | Pennine Middle Coal Measures Formation and South Wales Middle Coal Measures Formation Ⓤ | ||
| 7M 1705y to 9M 0715y | Diamicton | Till | Pennine Middle Coal Measures Formation and South Wales Middle Coal Measures Formation Ⓤ |
| 9M 0715y to 10M 0825y | Pennine Middle Coal Measures Formation and South Wales Middle Coal Measures Formation Ⓤ | ||
| 10M 0825y to 10M 1265y | Pennine Lower Coal Measures Formation and South Wales Lower Coal Measures Formation Ⓤ | ||
| 10M 1265y to 11M 0100y | Diamicton | Till | Pennine Lower Coal Measures Formation and South Wales Lower Coal Measures Formation Ⓤ |