A day at Tideswell, Derbyshire, with the OU Geological Society

Studying geology isn't just about reading books. To really get to grips with the subject you simply have to get out in the open air. With this in mind I recently joined the East Midlands branch of the Open University Geological Society, with the aim of getting a bit of practical geology experience, before I dive head first into the level 2 geology couse with the university.

So, the ‘Basic Geology Day’ at Tideswell, Derbyshire (click here for a map of the area) sounded like the perfect introduction for a relative beginner like me. It was designed to give people like me a gentle introduction to sedimentary and igneous rocks. S276, the geology course is all part of my master plan to get a geology based degree sometime before senility creeps in, but is not likely to figure until next year. The first question was, would I be out of my depth? Would an unintensional 'faux pas' see me ridiculed in such educated company? Not a bit of it! I was made to feel welcome right from the off and able to ask any question I felt necessary.

A group of eight gathered in the car park at the old railway station at Millers Dale which comprised four committee members and four ‘newbies’ of varying levels of geological experience. Not only was this my first geology field trip, but it was also the first outing for my brand new walking boots bought specially for this very day - quite obvious to all probably as said boots were quite unfeasibly shiny!

Anyway, after brief introductions, it was off on a short walk to the first stop – a limestone quarry, where Don Cameron, the group leader, described the ‘Derbyshire Dome’. Around 300 million years ago, the sea floor was lifted and a gentle anticline formed across what is now the Peak District, giving the area the characteristic 'dome' shape, hence the name. Folding of the rocks caused cracks (faults) to appear, particularly so within the limestone.

From the top down, the sequence of rocks present are coal measures; millstone grit; shale and limestone. The coal measures and millstone grit were then subject to erosion and at the most exposed upper part of the dome the gritstone was completely removed thus exposing the limestone in the centre of the Peak District.

A former Limestone quarry, Millers Dale Derbyshire.

Don suggested we all take a look at some of the rocks lying around the base of the quarry and seen in the foreground of the above photo. I was of course aware of the fossil content of limestone but not how numerous they can be. The rock that I examined was packed with vast numbers of brachiopods, rugose corals and crinoid stem fragments of varying sizes.

Limestone containing fossil coral (upper centre)

I won’t give you a detailed description of the geology of the day for fear of getting something hopelessly wrong and embarrassing myself, but what this day emphasised for me was that it doesn’t matter how much studying and reading you do at home or in a college, nothing quite matches seeing things out there in the great outdoors. Even something as straight forward as a fault or an unconformity means so much more when you see it with your own eyes and in three dimensions.

A fault line in the limestone caused during the formation of the anticline.

The day finished off with a quick drive up the road to take a look at a doloritic intrusion at Tideswell Dale Quarry, which was well worth the extra short drive. Here, hot liquid rock deep within the earth slowly cooled allowing fairly large crystals to develope forming the dark rock characteristic of dolerite.

Exposure of a dolerite intrusion, Tideswell Dale Quarry, Derbyshire.

Close up of the dolerite intrusion, Tideswell Dale Quarry, Derbyshire.

Close up of a recent rock fall at the exposure.

Some rocks (lower centre) exhibit severe weathering

and a redish colouration due to their iron content.

View towards Froggatt Edge (I think) which denotes the edge of the Millstone Grit.

To the left of the peak, lies shale and limestone.

So all in all, a fascinating intro to geology and the OU Geological Society. Sadly, I can’t make the next trip to The Roaches this Saturday (due to 50th birthday celebrations!), but I will definitely make the (for me) short journey to Bradgate Park in June to find out more about the oldest rocks in England.

Me and my boots can't wait!

Cheers, Alyn

Next up it's Darwin and Evolution

If only life wasn't so hectic and busy! If only I had the time to do what I REALLY want to do, namely study geology full time and blog away to my hearts content. Alas 'life' gets in the way so often and with my review of my fossil course only part done, I now have the course material for my next course in front of me. No time then, for that journey through time I'd hoped to do through the fossil record. Another time perhaps? I should be touching on it anyway, as I progress through the next endeavour.

For the next ten weeks or so, I will be immersed in everything 'Darwin' and 'Natural Selection'! On May 15th, S170 - Darwin and Evolution commences and it looks like it will be another fascinating course.

So many things about evolution and the fossil record puzzle me. For example, if evolution takes place slowly, there must have been innumerable transitional forms of all creatures, which logically should be represented in the fossil record. But, by and large this seems not to be the case. A first dip into the course book shows that Darwin believed the answer simply lies in the imperfections of the fossil record. The introduction hints at evidence for the important transitions in the history of life on earth, so I'm looking forward to finding out more and maybe dispelling a few myths. 

The course book we have been supplied with is called '99% Ape - How Evolution Adds Up', and there is also a DVD of programmes to watch. Strangely there is an experiment/project for us to undertake that involves collecting snails from the garden which is intriguing! Some past students have apparently been unable to take part due to a lack of said creatures, but there will be no such problems for me I don't think - we're over-run with the darn critters here in the East Midlands!

Unlike the previous fossil course which was assessed by a single computer marked assignment, this one will involve actually writing stuff and answering questions to be marked by a human! I much prefer that to be honest. You can't beat the personal interaction with a tutor so I'm looking forward to 'kick off' in 10 days time!

And!

This  next Sunday, 9th May I am going on my very first geology field trip with the Open University Geological Society - an 'Introduction to Geology Day' at Tideswell in Derbyshire, which sounds like the perfect way to start. We'll be looking at sedimentary and igneous rocks and I'm really looking forward to meeting new people and 'learning by doing' in the great outdoors. This will also be the debut for my brand new walking boots too! I'll let you know how it went next week!

Cheers for now!

Alyn.

Fossils and the History of Life : Part Three

Fossils and the History of Life: Part Three

Okay, I’d better crack on with my round up of S193, Fossils and the History of Life’.

Part Three: Common Phyla in the fossil record

As I mentioned last time, the animal kindom is split into groups called phyla. These are represented in the fossil record and the following is a brief summary of the main points concerning the most important animal phyla represented:-
Porifera:

• Sponges

• Cambrian to Recent
• Mainly marine though some freshwater
• Simple multicellular organisms – no nervous system
• Filter feeders
• Locally abundant fossils especially in Cretaceous rocks
• Found in flint nodules

Cnidaria:

Above: Coral fossil, Favosites turbinatus (Devonian)

• Corals
• Late Precambrian (Ediacaran) to Recent
• Almost entirely marine
• Colonial or solitary
• 3 groups: 1) rugose (solitary or colonial) Ordovician to Permian; 2) tabulate (colonial) Ordovician to Permian; 3) scleractinian (solitary and colonial) Triassic to Recent.
• Have central mouth and stinging tentacles

Note that Sea anemones and jellyfish are also cnidarians, but being soft bodied are rarely found in the fossil record.

Bryozoans:
• Also known as ‘Moss animals’.
• Ordovician to Recent
• Normally marine but also freshwater (uncommon)
• Very small colonial creatures living in groups of several to thousands of individuals
• Feed through tentacles
• Fossils can resemble corals and graptolites (see later)

Brachiopods:
• Cambrian to Recent
• Entirely marine and benthic (sea floor dwelling)
• Consist of 2 parts or valves and shells made up of calcium carbonate mainly though some of calcium phosphate.
• Filter feeders
• Are common fossil in Palaeozoic limestones and shales.

Molluscs:
• Cambrian to Recent
• Mainly marine.
• Very diverse phylum and most abundant large invertebrates in the fossil record.
• Phylum includes: bivalves; gastropods and cephalopods

Brachiopods seem rather similar to bivalves in many ways, but differ in that their ‘plane of symmetry’ passes through both valves rather than between them. Invariably, one valve is larger than the other in a brachiopod hence the common name of ‘lamp shells’.

Gastropods are aquatic, living in shallow marine and freshwater environments.

Cephalopods are entirely marine; have chambered shells and include ammonites, belemnites and nautiloids.

Echinoderms:

Above: Echinoderm fossil, Orophocrinus stelliformis (Lower Mississippian - 345ma)

• Cambrian to Recent
• Entirely marine are benthic, sessile (fixed to rocks) or vagrant (move around sea floor).
• Feed, respire and move using extendible tentacles called ‘tube feet’.
• Echinoids commonly has 5 rayed arrangement of plates and tube feet.• The phylum includes sea urchins, starfish (asteroids) and brittle stars (ophiuroids) and sea lillies (crinoids, see below).

Above: Crinoid fossil, Macrocrinus mundulus (Lower Mississippian - 345 ma)

Arthropods:
• Cambrian to Recent
• The largest animal phylum
• Found in land and water habitats.
• Includes: crustaceans, insects, spiders, and now extinct groups such as trilobites
• Have hard outer segmented exoskeleton which is periodically shed to allow growth

Above: Trilobite fossil, Greenops boothi (Middle Devonian)

• Exoskeleton comprises chitin and possibly strengthened by calcium carbonate or phosphate.

Hemichordates:
• Cambrian to Recent
• The most important group of hemichordates are the extinct and entirely marine graptolites. These are confined to the palaeozoic era and are therefore an important zone fossil. (see later) These look strangely like ‘saw blades’ where the ‘teeth’ are actually small recesses that house individuals that make up a colony.

Chordata:

•  Cambrian to Recent
•  Possess a notochord through the length of the body
• Include the 5 classes of vertebrates i.e. fish; amphibians; reptiles; mammals and birds.

Above: Dinosaur fossil, a juvenile Tyrannosaurus rex, (Cretaceous) located at the Burpee Museum of Natural History, Rockford Illinois, USA.

• Extinct groups include the land dwelling dinosaurs (see above); marine ichthyosaurs and plesiosaurs; and the flying pterosaurs.
• Vertebrate fossils are rare and usually comprise only fragments.

So that's a brief and way too rapid round up of the common phyla in the fossil record. The phylum 'Chordata' itself could warrant an entire blog on its own - as indeed any of them could. But I'll maybe do that at a later date if time permits. Next time I wil start that journey through time, starting with a look at the mysterious Ediacaran fossils, examples of which were found close to my hoome in the East Midlands, at Bradgate Park. Then I'll get down to the nitty-gritty of the 'Cambrian Explosion'.


All photographs included above were courtesy of 'The Virtual Fossil Museum' web site. This is an excellent resource, providing photographic galleries of the fossil groups and a lot of other information besides. For a closer look click here.

Cheers for now,
 Alyn.

Course Result!

Greetings Folks!

I interrupt the series of S193 summaries to bring you the long awaited result of the fossil course, just announced by the Open University . . .

Well, I PASSED. Hoorah!

Mind you, I would be pretty devastated to have failed it. A pass mark of 40% shouldn't be beyond anyone with a modicum of interest in palaeontology to be honest, but I did surprise myself by achieving a whopping

97%

If I had got anything around 80% I would've been quite happy, but getting 97% just makes me wonder how I managed to lose those 3%!?! Anyway, detailed feedback will arrive by post soon I believe, so I'll let you know!

Next up in a day or two will be Part 3 of my S193 summary.

See ya then!

Cheers,
Alyn.

Fossils and the History of Life: Part Two

Here is the second part of my summary of Open University course “S193: Fossils and the History of Life’.

 

Part Two: Fossil Classification and Evolution

Before anyone can get really stuck into palaeontology, an understanding of how fossils are named and classified is a useful starter. Immediately one is confronted with Latin which to many is the stuff of nightmares, but is actually really pretty straightforward in its use in science. Basically, fossils are classified according to the binomial system developed in the 1800s. Here, living things are classified according to a series of groupings in what is called the taxonomic hierarchy.

Firstly, we have the category ‘Kingdom’ and any organism can be classified as either ‘animal’, ‘plant’ or ‘fungi’. Within each Kingdom, organisms fall into broad groups according to their body arrangement or ‘bodyplan’ and these groups are called ‘Phyla’, (singular ‘Phylum’), an example of which is ‘Chordata’ which includes all vertebrates. Phyla are then subdivided into ‘Class’ such as ‘Mammalia’ that is mammals, obviously. The next subdivision is ‘Order’, for example ‘Carnivora’ , e.g. dogs, cats and these then constitute the next division, called ‘Family’. Cats are from the family ‘Felidae’ and include lions, tigers and the domestic cat.

Now, to get to the important bit – two final subdivisions serve to identify a specific species and make up the two parts of the specie’s binomial name. Below ‘family’ lies the category ‘Genus’, e.g. Felis which includes all wild and domestic cats. Finally, individual species are given a (not surprisingly) ‘Species’ name, e.g. catus for the domestic cat. So, the domestic cat is given the name Felis catus while us humans are called Homo sapiens. The observant amongst you will have noticed that the genus name must start with a capital letter while the species name does not and the whole name is written in italics. If you are hand writing an essay (does anyone hand write anything anymore?) then the whole name must be underlined.

Additionally, sometimes one may see what appears to be a surname after the species name. This in fact denotes the name of the person who first described the species in that particular genus. This is generally restricted to formal scientific journals though.

Giving any fossil a species name isn’t as simple as it might first seem. For instance, a ‘species’ is a group of organisms, the members of which can all interbreed. If one discovers a group of fossils, it is unfortunately not possible to determine if they could interbreed! So fossils are invariably categorised on their morphology alone.

Evolution and the fossil record:

A common definition for evolution, taken from the S190 course book is:-

“Evolution is any cumulative change in the heritable characteristics of species or populations from generation to generation or over longer periods”.

Or, more simply, it can be said to be ‘descent from an ancestor and modification of biological features with time’.

Charles Darwin and others had the nerve to suggest in the mid 1800’s that species were not fixed at all but actually changed with time. Darwin and Alfred Wallace were the first to actually come up with a mechanism for this to occur – by way of ‘Natural Selection’. Darwin of course published his ground breaking book ‘On the Origin of Species by Way of Natural Selection’ in 1859 and the whole idea of nayural selection can be summarised in 3 points:

 

• Members of any population will vary and such variations will be inherited by their offspring.

• A population will produce more offspring than can possiblys urvive and reproduce.

• Every population will experience a ‘struggle for existence’ and the offspring that vary in the ways most suited to their own environment will survive and breed again, causing the favourable variations to accumulate in these populations by ‘natural selection’.

A nice quote from the course book is “variation is the raw material on which selection acts”. So natural selection brings about biological change in a gradual and accumulative way.

Now this seems okay until one wonders, as I do, how did say, a birds wings gradually develop? At what point did this part-developed creature suddenly flap its new feathery arms and say, “well what d’ya know? I can fly!” Darwin, needless to say, had an answer – The Principle of Preadaption.

Feathers it is believed began firstly, merely as insulation and were in fact modified fish scales, a chance modification that just happened to help with insulation. Further gradual changes ultimately allowed flight – a radically different function to the original.

S193 has given tantalising introduction to the subject of evolution and so enrolling on another OU short science course, ‘S170: Darwin and Evolution’ will be a natural progression. Roll on May 15th! So many questions await, such as:-

• If evolution is gradual, why aren’t there examples of a line of fossils of a creature that highlight how it has changes over millions of years? Or are there?

• Did the Ediacaran fauna really become extinct or are they in some way related to modern life forms. I currently find it hard to believe that they just disappeared to be ultimately replaced by totally unrelated creatures.

• Did the ‘Cambrian Explosion' really happen? How can all categories of modern animal phyla ‘suddenly’ appear as if overnight (geologically speaking)? Surely they too gradually evolved but if so, why does the fossil record not reflect this?

I will try to delve into the Cambrian Explosion issue at a later date, but I think it warrants a bit more reading first.

By the way, if anyone out there (a post graduate perhaps?) has any thoughts on this subject or anything to contribute, drop me a line. Remember, I’m just an Open University mature student, delving into something that has fascinated me for ages but hasn't done anything about it, until now!

Next time I will look at the common phyla in the fossil record and start a journey through time.

See you then!

Cheers,

Alyn.