A1-The Great North Road
Here's a list of the geological outcrops crossed by the Great North Road:
| London to Hatfield / Ware | London Clay |
| Hatfield / Ware to Baldock / Royston | Chalk |
| N. of Baldock to Biggleswade | Upper Greensand & Gault, Lower Greensand |
| Royston to S. of Huntingdon | Cretaceous: Chalk, Upper & Lower Greensand |
| S. of Huntingdon to S. of Wansford | Middle Oolite: Corralian, Oxford Clay, Kellaways Beds |
| S. of Wansford | Lower Oolite |
| Stamford to S. of Grantham | Lower Oolite |
| S. of Grantham to Newark | Lias |
| Roman route Stamford to Humber | Lower Oolite |
| S. of Newark to Newark | Lias |
| Newark to Retford | Upper Trias, Keuper Marls and Sandstone |
| Retford to Bawtry | Lower Trias, Bunter sands and pebble beds |
| Bawtry to Doncaster | Lower Trias, Bunter sands and pebble beds |
| Doncaster to N. of Wetherby | Permian, Magnesian Limestone |
| N. of Wetherby to County Durham | Lower Trias, Bunter sands and pebble beds |
| Around Northallerton | Upper Trias, Keuper Marls and Sandstone |
| Doncaster to Thirsk via York | Alluvial Drift over Bunter |
| Croft-on-Tees to Darlington | Lower Trias, Bunter sands and pebble beds |
| Darlington to Ferryhill | Permian, Magnesian Limestone |
| Ferryhill to Gateshead | Carboniferous, Coal Measures |
| Newcastle to Morpeth | Carboniferous, Coal Measures |
| Morpeth to Felton | Carboniferous, Millstone Grit |
| Felton to Berwick | Carboniferous, Yoredale Series |
Maps of British Geology Thanks to Dr. Ian West of Southampton University. These are the old maps but the geology hasn't changed for millions of years.
©Biff Vernon 2001