Author Archives: chelseacolwellpasch

Maritime Archaeology Field School 2014 – Phillip Island, Victoria

Flinders Technical Officer and Dive Coordinator John Naumann dutifully watching over student divers on a shipwreck site.

Flinders Technical Officer and Dive Coordinator John Naumann dutifully watching over student divers on a shipwreck site.

 

This year the Maritime Archaeology Field School run by Flinders University’s Maritime Archaeology Program is held on Phillip Island, Victoria from 2-15 February, 2014. As part of the continuous assessment requirement for the field school, students from around the world and Australia write team blogs about their experiences and research as they near the end of their first week in the field. The students are divided into four teams (red, blue, green and yellow) and each team is responsible for contributing to the data recovery and the recording of the various maritime cultural heritage projects. Projects that students are able to undertake include underwater shipwreck surveys, foreshore surveys, and geophysical surveys. All work is done in cooperation with Heritage Victoria. Besides having daily work plans and data processing, students also attend lectures by industry professionals, local historians and avocational archaeologists on various topics and projects within Victoria. The students in each team have different experiences and involvements during field school and their unique perspectives are captured in their separate blog posts as a way for them to reflect and learn from their experiences as well as practice public archaeology through the dissemination of project details. Over the course of the next few days, each team’s blog post will be published on Flinders Archaeology Blog for public viewing.

Let’s get Geophysical! Non-invasive Underwater Archaeological Survey Methods

Trends are not a new concept to archaeology. The patterns found in the archaeological record are what lead to the wider inferences made about past cultures or behaviours. However, the latest trend in archaeology isn’t about similarities in information sets or assemblages,but rather the movement towards in situ (in place) preservation of archaeological sites, especially in underwater archaeology. I use the term ‘trend’ loosely, as it implies that in situ preservation is a ‘fad’ that will become obsolete given enough time or with the arrival of a newer, en vogue concept. I actually believe the opposite is true, that in situ preservation is here to stay and that it is the future of archaeology, above or below the water. This is not so much my opinion, but more of an observation. Looking at the international legislation that surrounds underwater cultural heritage (UCH), one cannot help but see that in situ preservation is pressed as the primary approach (UNESCO, 2001: Article 2,5; UNESCO Annex, 2001:Rule 1) and in many introductory texts, non-invasive survey methods are considered the future (Bowens, 2009:5). We need to know what is under the seabed in order to know if archaeological sites lie beneath, but we are trending away from invasive methods of surveying like subsurface testing. This leaves non-invasive approaches like geophysical surveys and remote sensing.

Geophysics in underwater archaeology is the scientific study of features below underwater and under the seabed using a range of specialized instruments while remote sensing is obtaining images of a phenomena from a distance (Bowens 2009: 217). It is common for these two methods to be grouped together, as they both deal with the ability to collect large amounts of data quickly and understand the scale of the surveyed site without having to be directly on or necessarily near it. In the past, geophysics was used primarily for site prospection but has been applied more recently to research and site management (Bowens 2009: 103). Geophysical and remote sensing surveys allow for the coverage of large areas relatively quickly and economically. They are not meant to replace divers on a site, but aid in timely identification of site locations, site distribution, site boundaries, and sub-seabed phenomena and are particularly useful in environments with poor underwater visibility, strong currents, or any other environmental hazards. Geophysical and remote sensing surveying methods will be discussed and can be grouped into three types: acoustic systems, magnetometers, and submersibles. These methods are used over a large area to ensure complete coverage of the site and its environmental context and are very accurate when used with global positioning system (GPS) satellites and differential global positioning system (DGPS) land-based reference stations. Using both will increase site position fixing as DGPS makes range corrections for GPS satellites; the addition of an on-boat GPS antenna increases accuracy (Bowens 2009:94).

Acoustic Systems:

These systems are the most commonly used geophysical method for underwater archaeological surveying. Sonar,or sound waves, are used in order to obtain the desired information. Some forms of acoustic surveying systems are: echo-sounders, multibeam sonars, side scan sonars, and sub-bottom profilers (Bowens 2009:104). The general idea behind these types of non-invasive systems is to use reflected sound waves (echoes) to construct a picture of what the underwater site and bathymetry, or depth over seabed, looks like.  Figure 1 shows the different components and general setup for using side scan sonar. Side scan sonar uses a wide-angle pulse of sound (emitted from the towfish) and the strength of the reflected scattered sound to display an image (Figure 2). The coverage of the side scan sonar can reach over 100m on either side of the track line. The track line is a gap in between the two sides; its size varies by size of coverage and depth. It is a ‘dead space’ of sorts where there is too much interference between the two sides to get an accurate image. This problem can be countered by overlapping boat runs to ensure full coverage. Acoustic shadows are also important as they can give a general description of objects that sit proud (vertical) to the seabed (Bowens 2009:108), see Figure 2.

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Figure 1.  The components and set up of a side scan sonar (image created by author)

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Figure 2. The results of a side scan sonar survey (after Kainic 2012)

Echo-sounders and multibeam sonars are generally used to gauge vertical measurements or depth. Echo-sounders were first to be applied to maritime archaeology and used a single transceiver to send an acoustic pulse straight down to the seabed and read the reflection or echo on a single prescribed spot. Multibeam sonar (also known as swath bathymetry) records a continuous thin strip of depth directly below and to the side of the boat (Figure 3), effectively scans the surface of the seabed, and creates a 3D image via colour gradations to highlight depressions and outcrops, as represented in Figure 4 (Bowens 2009:106). Sub-bottom profiling is the only means to locate buried wooden material culture underwater; metal material culture will be discussed in the next section. Strong short pulses of sound are shot into the seabed sediment and ‘reflect’ anything that sends the echo back earlier than the rest. The two forms of sub-bottom profiler are single-frequency pulse (also known as ‘pingers’ and ‘boomers’) and swept-frequency pulse (‘chirp’) (Bowens 2009: 109). Using both devices ensures the best coverage and penetration of the seabed.

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Figure 3. The setup of a multibeam sonar survey (image created by author)

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Figure 4. The results from a multibeam sonar survey, red are closer to the surface while blue is deeper (after Cox 2012)

Magnetometers:

Magnetometers measure the strength of the earth’s magnetic field and are used to detect the presence of ferrous material (iron) by the variations they cause in said field (Bowens 2009:111). This may include both man-made objects, like the cannon in Figure 5, or geological formations. They are usually deployed in a towing array to inhibit interference from the tow boat and the data they collect are plotted (or ‘contoured’) according to varying magnetic intensities (Figure 6).

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Figure 5. The setup of an underwater magnetometer survey (image created by author)

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Figure 6. The results of a magnetometer survey (Spirek 2001: Figure 2)

Submersibles:

Submersibles for archaeological surveying come in three forms: remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and manned submersibles. They can perform many tasks including visual assessments or searches, and photography, thereby negating the need for divers in the water (Bowens 2009:112). ROVs are piloted from the boat and can be outfitted with an array of data-collection devices like acoustic systems or video recorders (Figure 6). AUVs can be outfitted with these devices as well, but are not piloted nor are they attached to a vessel. Manned submersibles can complete the same aforementioned tasks but with an on-board pilot for more control and precision. manned submersibles fall into three categories; commercial, tourism, and research (Kohnen 2005:121).  (Figure 7).

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Figure 6. The setup of a remotely operated vehicle (ROV) (image created by author)

 Carolyn sub

Figure 7. The Institute of Nautical Archaeology’s (INA) manned submersible Carolyn in operation in the Aegean Sea (Kohnen 2011)

We know that the goal is to try to leave the archaeological site in its original context, as well as the best non-invasive ways to survey it, but why go through all the trouble? As archaeology is an ever changing field that progresses in parallel with new technology, it is undeniable that the information we gather ten years from now will be of a higher quality and degree of accuracy than what we collect today. This means that whatever we choose not to disturb today may never need to be disturbed in the future. Yet we must still yield a high degree of archaeological data,and therefore non-invasive survey methods, like those mentioned above, are an investment for our future AND our past.

References

Bowens, Amanda (editor)

2009 Underwater Archaeology: The NAS Guide to Principles and Practice. 2nd ed. Blackwell Publishing, West Sussex.

Cox, Marijke

2012 Building an Estuary Airport Close to Sunken Warship Branded ‘Bonkers’. Electronic document, http://www.kentnews.co.uk/news/building_an_estuary_airport_close_to_sunken_warship_branded_bonkers_1_1416102, accessed 30/08/2013.

Kainic, Pascal

2012 Search and Recovery Side Scan Sonar. Electronic document, http://www.yousaytoo.com/search-and-recovery-side-scan-sonar/1924787#:image:2729577, accessed 30/08/2013.

Kohnen, William

2005 Manned research submersibles: State of technology 2004/2005. Marine Technology Society Journal, 39(3): 121-126.

Kohnen, William

2011 Carolyn‘s 10-year Aegean voyage for INA. Electronic document, http://nauticalarch.org/news_events/news_events_archives/prior_to_2011/carolyn_takes_a_break/, accessed 01/09/2013.

Schott, Becky K.

2013 The Wrecks of Thunder Bay: A Photo Essay. Electronic document, http://www.alertdiver.com/m/?a=art&id=780, accessed 30/08/2013.

Spirek, James

2001 Port Royal Sound Survey: Search Begins for Le Prince. Legacy, 6(2):28-30.

UNESCO 2001 Convention for protection of underwater cultural heritage.

Out of the textbook, into the trenches: the practicality of a field practicum

There is nothing more frightening for a fresh university graduate then traversing the job market for the first time with their new degree and a realistic fear of not gaining employment in their field. The ‘real world’ can be a scary place and with a specialized profession, like archaeology, the positions that are available may be rare and highly competitive. Undertaking a field practicum while obtaining your degree can be a great way to get a ‘leg up’ on the competition. This July, I undertook ARCH 8159-Maritime Archaeology Field Practicum that took place over a week on Hinchinbrook Island in far North Queensland. Besides the obvious benefits of obtaining 4.5 credits, in only a week, towards my Masters in Maritime Archaeology degree (MMARCH) and spending that week on a beautiful uninhabited tropical island, I also gained valuable work experience; established resourceful personal contacts, and; received practical guidance from course supervisors and peers.

[In transit to Hinchinbrook Island on a small charter ferry from Port Hinchinbrook, QLD in the early morning of 8 July, 2013; photo courtesy of: Chelsea Pasch]

[In transit to Hinchinbrook Island on a small charter ferry from Port Hinchinbrook, QLD in the early morning of 8 July, 2013; photo courtesy of: Chelsea Pasch]

It is through practical courses, like field schools and practicums, that one finds out what the physical aspects of ‘the job’ entails; archaeology as a verb, an action. As a student, you know about research, report writing, and deadlines. These translate well into the life of a professional archaeologist and little transition is needed besides learning new formats or report requirements. It’s the adaptability needed in the field, the uncertainty of variables like weather and transportation, and the psychological components, that can sometimes find their way on to your project, that are impossible to teach in a classroom. For example, over the course of the week we had five out of seven days with winds over 30 knots (over 55 kilometers per hour). We had four out of seven days with rain for the majority of the day, and showers just about every day. It is also difficult, for anyone, to live an entire week on an island spending all of your ‘awake time’ (and ‘sleep time’, as we shared tents) with the same eight people. While things can get tense, you can choose to take away insight into different personalities, how to deal with them, mediate, and help build your emotional intelligence, or workplace empathy skills. Alas, there is no syllabus written about “how to keep your field logbook dry and legible when it’s constantly raining” or “how to not take everything personally in the field”. Its experiential knowledge gained from ‘mistakes made’ and ‘lessons learned’ while one is out in the field. I guarantee that what you pack for your first field experience is nothing like what you’re going to pack on your second or twentieth field project. Suddenly having a fresh pair of pants every day is not worth the extra kilos in your pack by the tenth time you lift it onto your shoulders, and that expensive new jacket that’s supposed to be waterproof is only water resistant. You learn quickly what you don’t need and what you do. After digging numerous trenches by hand, I would’ve gladly traded my snorkeling gear for a shovel. During this past practicum I have experienced everything from a Cane toad jumping on my face whilst sound asleep in my tent, to hiking five kilometers in the sand in order to ‘dig holes’ quicker than the tide could fill them back up, and then hike five kilometers back to the start all while carrying gear. These are just a couple examples of some of the unexpected parts of working in the field that can only be understood by those who have experienced ‘doing archaeology’.

You may be asking; “what makes a field practicum different from a field school?” For the MMARCH program, ARCH 8152-Maritime Archaeology Field School is a core topic, meaning that it must be completed in order to fulfill the requirements of the degree. It is in the field school where you are first introduced to the practical component of Maritime Archaeology; where you are taught the foundations of how to ‘do Maritime Archaeology’. But it’s also where you are still undeniably a student in a class, an unconventional class, but a class none the less. The practicum is a topic elective that must be chosen by the student and is more likened to a job or internship. You must have completed the field school as a prerequisite to ensure at least some familiarity with fieldwork but it is expected that the students essentially be employees for the time they are in the field. You are expected to pull your own weight, like carrying gear every day to and from site, taking turns on the metal detector (which can start to weigh heavily on your arm after 15 minutes or so), or jumping in to help everyone back-fill the many trenches that were dug just about every day. We share the burdens and the triumphs.  This is where the true value of a field practicum lies.

[The practicum participants walking back to camp from North Shepherds Bay, Hinchinbrook Island, Queensland on 8 July, 2013; photo courtesy of: Chelsea Pasch]

[The practicum participants walking back to camp from North Shepherds Bay, Hinchinbrook Island, Queensland on 8 July, 2013; photo courtesy of: Chelsea Pasch]

Having completed now both the field school and the practicum, I can truly appreciate the experience I have gained by both, and recognize the variances between them. The field school is valuable as an introduction to fieldwork, field methods, and team dynamics; and the practicum for its introduction to the need for adaptability in the field and for the luxury of being able to make mistakes, learn from them, and have professionals available for guidance. Where you’re just not feeling like an overwhelmed student worrying about notes, terms, and performing academically, but having the confidence of a peer or employee; trusted with important project tasks, minimal supervision, and the pressure of performing professionally. The purpose of a practicum course is to provide invaluable field experience to students so they may feel confident in their abilities as an archaeologist in the field and so that they may successfully transfer the ‘proactively’ driven ‘book smarts’ of their degree to the ‘reactively’ driven reality of a project in the field.

It is no secret that I am an advocate for practicums in post-graduate degrees, especially ones as practical as archaeology. Flinders University offers an additional practicum course (ARCH 8156-Advanced Maritime Archaeology Fieldwork Practicum) as well as numerous field schools ranging from conservation (ARCH 8802) to geophysics (ARCH 8808). While the theory and research studied and performed while undertaking your advanced degree are equally important, it is the ability to know how to work in the field and the confidence of “been there, done that” that can really set you apart when the illusive job posting surfaces and you have more field experience than the other applicants. It may be enough to tip the scales in your favour. Even the personal connections you make on practicum, whether peers, supervisors, or informants, can be beneficial resources or references for future employment, projects, or field opportunities. I am not saying that doing the practicums will guarantee you a job, but I can guarantee it will not be looked upon as a waste of time or credits.