Year 13 Biology students visited Malham Tarn this week for their A level field trip. The Field Centre is situated at 377 metres above sea level, in the Craven limestone complex, a European designated Special Area for Conservation. It is also in the Malham Tarn National Nature Reserve, part of the Malham-Arncliffe SIte of Special Scientific Interest. On Monday morning we had a comfortable coach ride to the nearby town of Settle, followed by a minibus transfer up the steep narrow road to the Field Centre. After lunch, the afternoon was spent studying lithosere succession on a limestone scree slope. Tuesday morning started with bright sunshine and we wrapped up in waterproofs and wellies to walk along part of the Pennine Way to nearby Goredale Beck. Field work techniques were used to sample and identify freshwater invertebrates living in an aquatic ecosystem. Tuesday afternoon was spent observing the effect of livestock grazing in the calcareous grassland species by the Tarn. In the evening students planned their own studies of the effect of various environmental factors on the distribution of species. We then completed the individual investigations on Wednesday morning before setting off on the trip back to school.