I have been out the last couple of days undertaking fieldwork for a building stones project, but today I was treated to a glimpse of a gem of a little geological section being prepared. Those of us who work in geoconservation talk a lot about geodiversity but this must be the most geodiverse section I have come across. It is a trench, only about 100m long but displays rocks from the Precambrian, Cambrian, Silurian, Carboniferous and Triassic.

The trench runs across the crest of the ‘Malvern Axis’, a major monoclinal fold trending north-south through central England that brings up Precambrian (~677 Ma; Cryogenian) to the surface. The Malvern line separates the two Precambrian terranes of the Midlands Microcraton, Wrekin Terrane to the west and Charnian Terrane to the east, that forms the solid basement of England. These Precambrian igneous rocks are unconformably overlain by Middle Cambrian Malvern Quartzite, and then Upper Silurian (Pridoli) Raglan Mudstone, and Upper Carboniferous (Moscovian) Halesowen Fm. This sequence was folded and thrust during the Variscan Orogeny at the end of the Carboniferous into the north-south Malvern Axis. Extension during the Triassic produced normal faulting along the Malvern Line and deposition of Middle Triassic (Anisian) Bromsgrove Sandstone to the east in the Worcester Graben. All this is being exposed in just one 100m trench, albeit somewhat tectonically shortened.

Standing on the axis, this is the view to the east. In the trench, the light coloured material in the foreground is Precambrian Malvern Complex, succeeded by grey/green and grey Carboniferous, red Silurian muds and Triassic sands towards the car.

To the west, the white is Cambrian followed by Carboniferous and Silurian on the other side of the axis. Note that many of the lithological identifications are still tentative.

The section is still in the process of being created and is on private land, but should be stunning when finished.

Accretionary Wedge #36 Stuff Left Behind

I am already late for this month’s accretionary wedge which has already appeared at geosciblog. Anyway, in the spirit of better late than never, here is my contribution to the topic of “things left behind”.

Garnet Hornblende Garbenschiefer from Lukmanier, Switzerland.

Almost thirty years ago I was fortunate enough to undertake my undergraduate geological mapping work for my degree dissertation in the Passo del Lucomagno / Lukmanier Pass region of Ticino, Switzerland. I have already talked about some of this in Accretionary Wedge #27 “Important Geological Experiences” and Accretionary Wedge #11 “Field camp”.

Google Earth view of my undergraduate mapping area at Lukmanierpass.

The topography, quite naturally for the Alps, was fairly severe, the campsite where I was staying at Acquacalda was at 1800m, the top of the ridge to the south was 2600m, and I had to descend 100m from the campsite before starting to climb up the other side. When working on the southern ridge it would take a couple of hours to walk up to the base of the ridge. I would then eat my lunch early, leave my rucksack and, travelling light, start to work my way up the side of the ridge carrying just my mapcase, notebook and compass-clinometer. I would spend the rest of the day working upwards until about four in the afternoon and then rapidly descend back to the campsite, collecting my rucksack along the way.

The south ridge of my mapping area from the campsite at Acquacalda

After about three weeks, about halfway through my stay there, I was working up to the south ridge. I had already ditched the rucksack but collected a fair sized sample of high-grade gneiss. I was crossing a boulder field and noticed an interesting looking exposure up a steep face to my right. I put my notebook down on a rock, placed my map case on top of it, and my gneiss sample on that to stop it blowing away. I then headed up to the steep outcrop with my compass-clinometer thinking I could easily remember a couple of readings and rock details and return to record the information in my notebook. At the exposure I took a couple of structural readings and then noticed that the rock structure looked even more interesting up and to my left. I traversed across and took another three readings, committing all five to memory.

I then turn round to return to my notebook. To my horror all I could see was a large boulder field. Although I had a luminous yellow field notebook, I had placed a grey map case on that, and then a large rock on top of that. They were perfectly camouflaged. I descended to where I thought I had left them and still couldn’t see them. I started to hunt for them. After an hour a mild panic started to set in. Had I just lost three weeks work down to my own stupidity? Since I knew that they had to be in the boulder field somewhere, I decided that the only solution was to criss-cross the boulder field in a grid search.

After another two hours without success, time was beginning to run out. As I was mapping alone, I had an agreement with the two others I was camping with and who were mapping adjacent areas, to meet up at 5pm. In the case of one of us not being there at that time, the other two would go out to look for them in case something had happened to them. I was going to have to give up soon to make the rendezvous deadline. My map and notebook could be ruined by weather if I left them out, even if I returned to find them the following day.

I decided to do just another couple of passes. And there they were, right in front of me, I practically walked into them. I was so relieved. I realised I was only 10m from where I thought I left them in the first place. I went back to that point and yes, I could see them from that point once I knew where they were, but the camouflage had been excellent. It was time to go back. But not before I had recorded the details of the outcrop including the five structural readings that had been burnt into my memory over the past three hours.

So, I haven’t ultimately left stuff behind on this occasion, but there is a follow up to the story. After my degree, I went to Cardiff to do a Ph.D. and I told the metamorphic petrology lecturer about the wonderful metamorphic rocks at Lukmanierpass, including hornblende garbenschiefer and kyanite schists that were so shiny you couldn’t look at them in the sun without sunglasses. I showed him the box of my rock samples that I had collected there. He asked if he could hang on to them for a while and I agreed. With the passing of my Ph.D. I completely forgot that I had lent him the rock samples. I moved on to Keele, and he moved on from Cardiff. I don’t know what happened to those rocks, but I do wish I hadn’t left them behind.

Prezi – First Impressions

Yesterday I gave a talk at my university’s teaching innovation symposium on using gigapan and photosynth technology for providing and alternate learning experience for mobility impaired students who have difficulties undertaking geological fieldwork. As a potential teaching innovation for myself, and because I was going to be talking about using images at multiple scales, I thought it would be a good idea to experiment with Prezi rather than using a traditional PowerPoint presentation. I also thought it might be a good idea to blog my first impressions.

For those who are unfamiliar with Prezi, instead of having a number of individual slides, one has a single canvas on which all elements are arranged and a motion path is constructed between the elements. The presentation then follows the motion path, panning, rotating and zooming between the elements as necessary. This generates a smoother, virtually seamless presentation and this appeared to chime well with the zooming and panning of gigapan, and the theme of the talk that any alternative fieldwork experience must mimic the way in which geology students should approach an outcrop – overview first, the move in, examining features in detail around the outcrop, and then zooming out to reassess the exposure at a large scale.

[My most explored gigapan – Autobrecciated flow-banded rhyolites from Penfathach, Pembrokeshire]

The Prezi interface is quite intuitive following some simple tutorials with the placing and sizing of images and text. The presentations can be compiled on-line via their website for free (with a larger file storage allocation if you are in education) or they can be done off-line via a paid-for application. However, since there is a free 30-day trial of the off-line programme, I opted to try that. The basics are straight forward but I did find a few issues that did annoy me slightly. However, please bare in mind that I was using the software for the first time and I was under time pressure to write the talk quickly.

Image Size
What is not highlighted in the overview tutorials, but I did find in the ‘known issues’ section of the website only after I had written about half the presentation, was that the maximum permitted image size is 2880 pixels. Prezi will quite happily allow one to upload an image larger than this without any warning and issues only show up later when trying to show the presentation. Because many of my raw image from my Canon 5D are 4368 pixels I had to go back through the presentation, remove all the oversize images, resize the originals and insert the new copies.

What I wanted to achieve was an effect where I had an overview of an image and then zoom into some small text inserted over an important feature, to highlight it. This works well except when the text is below a certain size. In such cases, the background image disappears leaving just the text. Whilst I can see that in some cases this might be useful, it wasn’t the effect that I was trying to achieve and there seemed no way that I could control the level at which the image disappeared. The only thing that I could do was to enlarge the text or extend the line length until the image remained in the presentation by trial and error. This resulted in having some text on the images that was larger than I really wanted.

Also the image vanishing wasn’t consistent. To rearrange things on the canvas, one can group them, move the group and then delete the group container leaving the moved elements. However, sometimes just moving an image with its text will cause an image to disappear when it remained before it was moved. Also, non-disappearing images in the off-line presentation would vanish when the presentation was uploaded onto the on-line site for sharing. This inconsistency was infuriating as I knew the effect I wanted to achieve but it was very frustrating getting it to work, testing the presentation over and over again. I also had to check that it also all worked at the resolution of the projected image as well as that when just editing on the laptop at a higher resolution.

Our university has only recently upgraded its wifi network. They have done a very good job (I can now connect to it on my iPhone for example where I couldn’t previously as it used a java login applet) but presenting in an unfamiliar room I wanted to not risk possible network issues and have every thing embedded in the presentation. Consequently, I used Camtasia to capture some demos of gigapans on the web and in Google Earth. Theoretically, the off-line version of Prezi can take a uploaded video file and then insert a converted file into the presentation. I simply couldn’t get this to work irrespective of which video format I tried to save the files in. I then tried uploading the videos to YouTube (successfully) and then insert these into the presentation as I had seen in the demonstrations. However, this would appear not to work using the off-line version. So I uploaded what I had of the presentation onto the Prezi website and then tried to insert the YouTube clips into this. This also failed to work.

By now I was running out of time. I had a half finished presentation and not much time left to complete it. I made the decision to put my trust in our IT people and their new wifi network, and break out of the presentation to run the gigapan, photosynth and Google Earth demos live. My trust was rewarded and everything worked on the day but there was more faffing about swapping from presentation to chrome, Google Earth and back than I would have liked.

I have subsequently discovered that if you enter the YouTube short URL as you are prompted to do by Prezi, this doesn’t work, but if you use the long URL from Camtasia or the advanced options from YouTube, it does. Consequently, I have now embedded some short clips into the presentation below.

When it came to the presentation there were a few issues too. First, I like to walk about a lot when I present and use a remote control device to advance sides. However, all this does in Prezi is to zoom in or out of the canvas. I had to stand by the laptop on the lectern to advance the presentation manually. The layout of the room was such that the computer console lectern was one side of the room and the projection screen was the other. It was also very side on so I couldn’t easily see the projection screen from where I was giving the talk so I spent far too much time looking as the computer screen and not interacting with the audience. Manually advancing the presentation is done using the arrow keys. However, I am very used to PowerPoint where the advance can be done by hitting the space key, which is much easier. Unfortunately, in Prezi this swaps from presentation to edit mode. I did this several times by instinct and it did disrupt the flow of my talk.

I am also very accustomed to the presenter view in PowerPoint where you can see the next side coming up as well as the current one on the screen of the presentation laptop. This really aids the flow of my talks now and a couple of times I was a bit lost without it.

Would I use Prezi again? Very possibly. The effects are good and the presentation does stand out from the PowerPoint fatigue. With a little more practice and in a lecture theatre with a better layout I think the talk could have gone better. However, the inability to use the remote, pace about, interact with the audience and know what was coming next did hinder my delivery. Despite the greater complexity and fiddliness of putting a talk together I would probably use this again for conference presentations as I think the presentation did stand out, but for day-to-day lecturing use I’m sticking with PowerPoint. PowerPoint also allows the easier creation of lecture notes for students.

You can judge the results here. Obviously, there is no audio with this presentation but you should get the general idea.

Accretionary Wedge 34 : Weird

Dana Hunter at En Tequila Es Verdad is hosting this month’s Accretionary Wedge with the topic of Weird.

First, here is an exposure from last weekend’s Llangollen mapping course.

Folded cross beds and weird tafoni

Weirder still is the fact that the tafoni are not salt weathering related.

Second up, is something I put up for accretionary wedge 6 (things that make you go hmm – back in 2008) but I like it a lot so I’ll put it up again …

What happens to the orange sandstone and the faults?

You can see a wider view in the gigapan below.