Findochty – Portknockie – Cullen – Findlater Castle. Day 2. Excursion to the Banffshire Coast

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Unpublished report prepared for the Edinburgh Geological Society Excursion to the Banffshire Coast. 14th – 21st May, 2005. Leaders: John Mendum, Douglas Fettes, David Stephenson and David Gould (British Geological Survey)

Findochty [NC 466 683]

(Figure 23)

Proceed towards harbour but turn right into South Blantyre street. Park at the public area next to beach.

The locality shows the nature of the Findochty Quartzite Member of the Cullen Quartzite Formation (Grampian Group). A walk ENE along the beach (quartzite outcrops) leads to a gully where till can be seen overlying glaciofluvial red sands of the Blackhills Sand and Gravel Formation (Late Devensian).

Portknockie [NJ 495 689] and [NJ 487 687]

(Figures 23, 24; Plates 5, 6)

Drive to the harbour and park as available. Go to northeast side of harbour to examine sections west from garage. Section in Findochty Quartzite Member of the Cullen Quartzite Formation (Grampian Group) showing micaceous and feldspathic psammite and quartzite with subsidiary garnetiferous semipelite beds. Excellent examples of ripple-drift and larger scale cross-bedding. Note folding and lineation. Immediately above the end of the harbour wall cross-bedding and convolute bedding show exaggerated oversteepening (care with climbing up and down).

Return to vehicle and drive to east side of Portknockie following signs to Bow Fiddle Rock. Short walk to viewpoint to see the marine erosion feature. Thick beds of quartzite of the Findochty Quartzite Member dip c. 45° to the SSE and have been selectively eroded.

Cullen Shore, Logie Head, West Sands Bay and Findlater Castle [NJ 512 675 to NJ 542 673]

(Figures 23, 24, 25, 26; Plates 8, 9)

The walk along the foreshore (good path mostly) will traverse the Cullen Quartzite Formation, including the Logie Head Quartzite, Dicky Hare Semipelite and Sunnyside Psammite members. Note that the beds generally dip steeply. The units are traversed at first at a shallow angle to the strike, but later around Logie Head across the strike. The quartzite show good cross bedding and other sedimentary features (even though metamorphosed to amphibolite facies) and the more semipelitic units show tight folding and locally prominent small garnet porphyroblasts. In Sunnyside Bay we pass into the Findlater Flag Formation (Lochaber Subgroup), here with the West Sands Mica Schist Member at its base. The bulk of the Findlater Flag Formation is made up of thinly bedded micaceous psammite and semipelite, but at Findlater Castle a prominent quartzite, the Findlater Castle Quartzite Member is well exposed. Large-scale ripple marks are seen on a near vertical bedding plane. The buses should be at Barnyards of Findlater farm.

Selected bibliography

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