The scope of the articles included in this issue are as diverse as the science of geology and as Bill Baird's contribution on the subject of 'tektites' reminds us, not solely confined to this earth. I hope that the selection of topics covered in this edition will provide both interest and, as with Joanne Cavill's view of the Yellowstone National Park, a stimulation to the Society's members to explore the natural wonders which our world has to offer. For those with an interest in riches of another kind, Mike Gallagher and Don Cameron bring us up to date with the state of gold exploration in Britain. Mike Cotterill, on the other hand, delves into the rich but diverse world of micro-organisms throughout geological history. 

I would like to express my thanks to the Director of the British Geological Survey for permission to reproduce the plate of Pterichthyoides milleri form the photographic collection at Murchison House. This fine specimen from the Achanarras quarry in Caithness, held in the custodianship of the Royal Scottish Museum, provides our link to John Hamptons' celebration of the l50th anniversary of Hugh Miller's The Old Red Sandstone, and testimony of one of Scotlands most passionate geological thinker. 

In our book reviews, Mike Browne expresses the general sense of disappointment felt by many in the 3rd edition of the 'Geology of Scotland'. The 'Directory of mineral and gemstone locations in Scotland' by Kenneth Pickering has similarly been received with mixed feelings by many mineral collectors. Whether any new works will suplant 'Heddle' as our fountain of mineral knowledge remains to be seen. 

The remainder of Issue 27 includes an addendum to the Proceedings of the Society for the 156th Session (1989-90) presented in Issue 26, together with the Proceedings for the 157th Session (1990-91). The former completes the statuary listings of Council, office bearers and membership of standing committees of the Society during the 156th Session. The Proceedings of the Society for the 157th Session presents a resume of the activities and business during 1990-91. Tucked away in the 'Council Notes' is a rather short reference to the guided walk of Holyrood Park. This event deserves greater mention for its importance in increasing public awareness of the geological sciences. The fact that 70 people had, regrettably, to be refused is testimony alone. I feel we must express our appreciation to David McAdam and David Land for their time, effort and enthusiasm in presenting the history of perhaps Edinburgh's most famous landmark.