Yorkshire OUGS visit to Forge Valley, Saturday, 13 March 2004

Very rough sketch map This is a very rough sequence of the rocks we looked at on the trip (not to scale!) - these Middle and Upper Jurassic rocks are exposed where the glacial melt water cut the channel in Forge Valley where the River Derwent now runs. (LCG = Lower Calcareous Grit; MCG = Middle Calcareous Grit).  All the beds dip approx 5° South Eastwards
Looking across towards Hackness  - this is where "Hackness Lake" would have been, the shoreline indicated by the tree line on the hill at the back to the left, which is the boundary between the Oxford Clay (farmland) and Lower Calcareous Grit above.  Photo looking North West. "Lake Hackness" from Forge Valley woods
Displays along the path, showing local fauna, etc As we climbed up the hill, the flora and fauna gave an indication of the soils and rocks beneath - this area had lime-loving plants such as Dog's Mercury and wild garlic.  Further on, the Oxford Clay often slips, and the trees compensate by "bending" as they grow in their new location. Beyond that were different species in the Lower Calcareous Grit area - the lime had leached out, giving acid soil (no beech or ash!)
Trees growing over Oxford Clay Looking North East - stone was used for sharpening tools
Tree trunks bent to compensate for the landslip Whetstone quarry - Kellaways (Langdale Member) - lots of bioturbation evident
My pen got around a lot! Used here for scale Passage Beds - were considered to be a transition between Lower Calcareous Grit and Malton Oolite
Trace fossils were abundant (above pen) At the top of the hill, farmer's wall built of Passage Bed stones
Stone was quarried here for smelting iron, and for building Lots of shells evident in the rock
Wallace's Quarry - looking NNE Malton/Hambleton Oolite - razor shell
Ooids clearly seen Layers of bentonite between the oolitic beds
Through the magnifier - oobiosparite Whitestone Quarry - more oolite, Middle Calcareous Grit above
Whitestone Quarry Dave and John were the intrepid explorers in the bottom of the gill
Bentonite - volcanic clays - where were the volcanoes?  Jointing clearly visible here - where this rock is below the river, there are sinkholes where the water runs off through the joints Sieve Gill - exposure of oncalitic limestone below Malton Oolite - we discussed how the gills had come about - outwash channels from glacial meltwaters?
Sink hole as mentioned above Peter shows us the corals
This is a sink hole beside the Derwent - and finally! - A coral reef in amongst the Oolite!  Thanks to Peter Robinson for guiding us so well and sharing your knowledge, and Ann for arranging the weekend.
Back to Geology Field Trips page Scalby trip on Sunday, 14 March 2004