From 2-3 March, Iziko’s Maritime Archaeology department organized a Remote Sensing and Recording in Archaeology workshop for the UCT Archaeology Honours class. The students heard lectures from the Iziko staff, but also had three guest lecturers. Remote Sensing is a catch-all phrase to describe the technologies utilized by archaeologists to find sites. We were fortunate to have Henk Steyn from PGS Heritage, a contract archaeology firm, demonstrating the mysteries of Ground Penetrating Radar.
GPR works by transmitting high-frequency radar pulses sent from a surface antenna into the ground. These pulses are reflected back differentially by the deposit it is sent into. The time differences between the reflected pulses are measured and that enables the operator to create profiles of the subsurface environment. The students each got a chance to use Henk’s instrument after which he showed them how to analyse the data collected. Next up was Jaco Boshoff, delving into the mysteries of the earth’s magnetic fields and magnetometers – the instrument used to measure those fields. If any magnetic material is buried (for example anchors or cannons), it will distort the Earth’s magnetic field and show up in the readings from a magnetometer. Jake Harding finished the day by amazing the students with the secrets of photogrammetry and 3D recording.
Day Two started with Wilhelm van Zyl from the Council for Marine Geoscience expanding on the use of multibeam sonar and how it can be used to find shipwrecks and ancient coastlines. A multibeam echosounder is a type of sonar that is used to map the seabed. It emits acoustic waves in a fan shape beneath its transceiver. The time it takes for the sound waves to reflect off the seabed and return to the receiver is used to calculate the water depth.
Next, Chris Keightley from Optron, a company that sells survey grade GPS units, unveiled the mysteries of high-powered differential GPS, very important for recording the position of any sites found as accurately as possible. Jake Harding reminded the students that it was important to organise the collected data in an orderly manner by designing custom made recording forms for collecting data as diverse as surveying measurements to the descriptions of anchors and shipwreck timbers.
Jaco continued with an introduction to the history of shipbuilding and ship construction. He elaborated by showing some of the shipwrecks Iziko has excavated in the past. Anna Boot finished the workshop off by inducting the participants into the art of illustration. Accurate artwork is often used by archaeologists to illuminate special features on important artefacts. Feedback from the students indicated that they thoroughly enjoyed the new avenues of research they’d been exposed to and that they hope to join the Iziko Maritime Archaeology team in our future fieldwork adventures.
