Ilkley Moor

© Craven & Pendle Geological Society

Cow and Calf Rock

Cow and Calf

Trace Fossil

Trace Fossil

Glacial Moraine : Riva Reservoir

Glacial Moraine : Riva Reservoir

From Left to Right:
Harold Lancaster, Jack Soper & Paul Kabrna

The field visit to Ilkley Moor began with a look at the spectacular Cow & Calf Rock. This rock is formed by the Addingham Edge Grit; a typical coarse-grained cross bedded sandstone belonging to the Carboniferous Millstone Grit Group. The large prominent outcrop is the Cow and the displaced smaller boulder to the right is the Calf. It measures 8 metres tall, weighs about a 1000 tons. It is reasonable to suppose that the last glaciation had a part to play in dislodging the Calf boulder in the first place and then perhaps holding back its downslope movement.

The quarry revealed ripple marks and trace fossils as shown in the photograph to the left. The ripple marks were formed by wave action which suggest that the water must have been shallow.

Other noticable features seen in other rock outcrops were glacial striae (indicators of the direction of glacier ice movement) in Hangingstones Quarry, and 'cup and ring' structures on a large boulder know as The Haystack. These curious structures are thought to be about 4000 years old, perhaps of end Neolithic to early Bronze Age.

Our climb towards the top of Ilkley Moor led us to the Lanshaw Delves moraine. The morainic ridge is aso notable for its excavation pits (places where man may have extracted limestone clasts from the moraine, perhaps for agricultural lime.

On our walk towards Riva Reservoir the party descended down Coldstone Beck. The beck has exposed evenly laminated fine-grained sandstones which were probably deposited from suspension by tidal currents by the Addingham Edge Grit.

At Riva Reservoir the Lanshaw Delves moraine is exposed in cross-section and shows a wide variety of poorly sorted clast sizes in a clayey silty sandy matrix. Most of the clasts are of sandstone but fossiliferous limestone clasts can be found particularly on the shore of the reservoir.

The views are quite stunning and in the picture to the left at my eye level you may just be able to make out the 'Golf Balls' of Menwith Hill! Harold is enjoying the view while I'm in the middle of serious geological discussion with Jack Soper . . . .