SideTracked EarthCache - Bristol Temple Meads
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The third attempt of a cache at Bristol Temple Meads railway station, previously GC2KJWB then GC5WX87. This one is an EarthCache intending to give a break for cachers between trains. That said, the Earthcache is outside the station, so can be done by anyone else too!
Bristol Temple Meads is the oldest, largest and main station in Bristol, the first to be built by famous engineer Isambard Kingdom Brunel in 1840 as part of his Great Western Railway to London Paddington. Originally the western terminus of the railway, a track was later built to Exeter St Davids. Over time, many more lines, both national and local, have been built to pass through, or end at, Temple Meads. The station's name comes from a combination the nearby Temple Church, and Mead, a shortened version of 'meadow', referring to a nearby meadow that existed in Bristol when the station was built.
Oddly, the platforms are numbered from 1 to 15, but Platform 2 isn't in use and 14 doesn't exist at all.
To log this EarthCache, please send the answers to the following questions by email or message. Due to owning many EarthCaches I receive numerous emails per day so there is often a delay in replying, therefore feel free to log before awaiting a reply. Only answers that are drastically incorrect or photos that reveal answers will be deleted.
1. What are the colours you can see in both the stones AND the matrix? Would this fit the description of a puddingstone?
2. What is the size of the largest stones in the matrix? As a guide, a 10p coin is 25mm in diameter.
3. In the pillars, name some differences between the conglomerate and the yellow sandstone.
The Earth science:
Much of the exterior, and some of the interior, of both the old and current stations is built from a rock called 'dolomitic conglomerate'- a long phrase, this is what it means:
In geology, a conglomerate is a clastic sedimentary rock containing a substantial amount of sizeable pebbles/gravels, larger than 2mm, compacted together within a matrix of much finer materials (haematite and dolomite) that make up the surrounding rock, hence the 'dolomitic' prefix. This particular stone was quarried from Draycott, near Cheddar.
Pudding Stone is similar to the composition of a congolomerate; the main difference is that the stones in a puddingstone are significantly different in colour to the matrix, so it looks like a slice of fruitcake (with a fair bit of imagination!)
An example of puddingstone with rocks very different in colour to its matrix.
The old station wall has many support pillars, with alternating rocks made of dolomitic conglomerate, and also sandstone.
Sandstone is another sedimentary rock with very fine grains- similar grain size to sand, hence the name.
(No hints available.)