Twenty people gathered for Ian Chisholm's interesting discussion about what geologists still don't fully understand about the Millstone Grit in the Huddersfield district.     We looked at several exposures in the Pule Hill area above Marsden.     The weather was cold and miserable but we went to the Carriage House hotel for a decent lunch and a good talk.

Ian is trying to account for the depth of water in which the sands and shales were deposited, their rates of deposition and how much space was needed for the 2 Km deposition of sediment.

We looked at the Goniatite Gully exposure of fossiliferous shale, on Mount Road, Marsden.     Then we walked down to a clough on the south side of Mount Road which exposes more shale and the gracilis goniatite marine band.     This had been previously investigated so we knew its exact position.

There has been a recent rock fall at Worlow Quarry, just to the east of Pule Hill, so we could see very fresh examples of the down faulted Pule Hill Grit.     The summit of Pule Hill is also made up of Pule Hill Grit.

The cyclic nature of the deposition of sand and shale was discussed in terms of sea-level changes in the mid Carboniferous due to glacial cycles in the Gondwana ice sheet, which are probably related to the solar Milankovich cycles.

Many thanks to Ian for a full day of fascinating discussion.

Sheila and Harold Dyson have been the prime movers in this project.     They have written the leaflet and completed the way marking of the two geological walks, with a bit of help from Andrew Kraskinski, Brian Farrington, Alison Quarterman and Richard Bell.

The leaflet will be launched on Saturday May 13th at the Jubilee Tower, Castle Hill, with the help of the Castle Hill Countryside Warden, Julie Brown.     We hope to get some publicity to aid sales of the leaflet at Tourist Information Points as well as museums and bookshops in Kirklees.

Sheila will take guided walks around the two trails the following weekend, as part of Yorkshire Geology Month.

For most of recorded history, the cause of earthquakes has been attributed to mythical beasts or the wrath of Gods!     However, the first rational explanation of earthquakes, beyond mythical stories is from Greek natural philosophers.     Aristotle (4th century BC) proposed that the cause of earthquakes consists of the shaking of the Earth due to dry heated vapours underground or winds trapped in its interior trying to leave toward the exterior. These ideas stood the test of time until the 17th century when A. Kircher (1678) related earthquakes and volcanoes to a system of fire conduits inside the earth.     In the 18th century M. Lister and N. Lesmery suggested that earthquakes were caused by explosions of flammable material concentrated in some interior regions.

The great Lisbon earthquake (1st November 1755) which caused immense destruction and generated a large tsunami ultimately proved to be the starting point of modern seismology (a term derived from two Greek words: Seismos = Shaking and Logos = Science or Treatise).     In 1760, J. Mitchell, an astronomer working at Cambridge, was the first to relate earthquake shaking to the propagation of elastic waves inside the Earth.     He is also on record as being able to calculate the location (epicentre) of an earthquake.

Significant progress began in 1857 when an Irish engineer, Robert Mallet, mapped earthquake zones around the Mediterranean and suggested that earthquakes were elastic waves of compression caused by the sudden flexing and fracturing of the Earth's crust.

By chance, an English geologist and mining engineer called John Milne, who was working in Japan in 1880, witnessed a severe earthquake in Yokohama. This experience had a profound affect on him.     Milne considered that a means of detection was called for.     In collaboration with Ewing and Gray, Milne was instrumental in developing an accurate seismograph for recording vibrations produced by earthquakes.     This work dominated the life of John Milne who today is considered to be the founder of modern earthquake studies and the science of seismology.

This talk will explore the life of John Milne and his contribution to earthquake studies.

We are taking advantage of the North Pennines Festival of Geology and Landscapes organised by North Pennines A.O.N.B Partnership.     www.northpennines.org.uk     This festival includes many activities including walks, mine visits, lectures and exhibitions, led by local geologists.

Join us on this weekend to participate in five or six different visits, including lead mines and museums, visits to areas with limestone and shales and a visit to High Force in Upper Teesdale.     Most of the field trips require booking in advance and some have a booking fee.     Talk to Alison (01484 608004) who can coordinate lifts in cars and make arrangements for booking field trips.

Some of us will be staying in the Youth Hostel in Alston (01434 381509) but please book your own accommodation.     Alston has restaurants and pubs so we can eat out if we want to but the Youth Hostel has facilities for self-catering, so it would be sensible to take food for breakfasts, drinks and packed lunches.     There is bed and breakfast accommodation in Alston and the surrounding areas.     For more information on places to stay contact the Alston Tourist Information Office (01434 382244).

Some people are free on Friday and can drive up on Friday morning to participate in a field trip on Friday afternoon.     Others may have to drive up on Friday evening ready for the Saturday and Sunday field trips.     Please offer your car for lifts for those who do not have their own transport.

Ian Chisholm, Tony Benfield and Colin Waters are taking a trip around Glossop on behalf of the Yorkshire Geological Society on Saturday 3rd June. This will include a visit to Winscar Reservoir, just south of Holmfirth.     They are looking at the sedimentology of the Huddersfield White Rock, which is also found around Meltham and Holmfirth.
Further details are available from the YGS website Yorkshire Geological Society

Teach yourself how to use British Geological Survey maps (the coloured ones): a talk by Alison Quatermann.

Alison has been asked to join with the Dry Stone Wallers to put on some guided walks for the general public in the summer.     Dates are as follows: