Date: 06 Nov.2010
Client: Imperial College London. Geology Group (1st to 4th.yrs) 30 students + 1 lecturer
Venue: Marquess of Anglesey Column; Newborough Beach + Llanddwyn Island; Gadlys Quarry + Trwyn y Parc; Llanbadrig
Detail: Marquess of Anglesey Column. Talk by Margaret Wood (MW) on the general geological background of Anglesey, and the glaucophane schist outcrop on the site. Inspection of the outcrop and collecting of rock fragments (no hammering!). Copies of the latest Kawai paper on Llanddwyn circulated. Newborough. Walk through forest to visit the banded cherts and the ‘new’ pillow lava on the Newborough Forest Geology Trail. Some chert samples picked up from the ground ( with a warning that they were sharp!). Copies of the Llanddwyn Island walk leaflet circulated.
Met up with MW at the classic pillow lava exposure on the beach for a talk on the mini tectonic plate that is Llanddwyn Island, the explosive eruption, volcanic ‘bombs’ and pillow lava formation. Warning about ‘no hammering’ and the danger posed by the cliffs and wet grass. Continued onto the island to visit the thinly bedded sedimentary rocks (deep ocean), and discussed the dropstones located by Kawai et al. Photographs and diagrams of the dropstones circulated ( from the paper). Brief talk on the St.Dwynwen story by the priory ruins, and the significance of the horses on the island.. Background of the lighthouse explained briefly and then through the fault from Porth Twr Mawr to Porth Twr Bach. Dolerite dyke examined in some detail, as were the melange exposures.
Hurried walk back to the transport and packed lunches in the car park (10 mins). Gadlys and Trwyn y Parc. Large limestone ‘clast’ described (¼ mile across), along with the likely effect of the graphite seen on the quarry walls. Examination and explanation of the potholes ( + exploration of the tunnel through the ridge-low tide!) and onward to Porth Padrig (White Lady) and met up with MW on the headland for a talk about the melange, the jasper pits, siderite and the Padrig Quarry (stromatolities etc.) Photos of St. Patricks cave circulated along with Cemaes Bay walk leaflet. Party led back to their base at Alternative Outdoors ( Rhoscolyn)