b'Environmental geophysics Environmental geophysicsWelcome readers to this issuesExcerpt that he included at the end column on geophysics applied toof his piece here; for me pretty much the environment. In this issue I amevery field excursion I have ever gone continuing the series that was startedhas some war story aspect to it (i.e. in the last Preview issue: reminiscencessomething that just didnt go right), by Niels Christensen on his career,even to the most benign of locations centred around Aarhus University, thatand simplest of surveys. I guess that is he called Seven Scenes. I especiallywhat almost always makes this work an enjoyed Niels short Adventuresadventure. Over to NielsMike Hatch Associate Editorfor Environmental geophysics michael.hatch@adelaide.edu.auPivotal moments: Seven scenes from a geophysics adventuremy activities for some time, it will look(DTU) and we were funded on a project rather mysterious. Fortunately, I neveron Deep Aquifers. The group was led by meet anyone; I have deliberately chosenProfessor Arne Villumsen who did not a very calm and quiet place in the foresthave problems with professional weight. around Fljstrup, about 10 km southIn the project there was money for the of Aarhus, as far away as possible fromacquisition of an instrument, and after power lines, buried cables, electric fencescareful investigations I chose the Geonics and other man-made installations thatProtem 47 instrument, which at that time might disturb the measurements. Herewas able to measure at earlier delay times I can experiment with what it takes tothan other instruments on the market disturb the recordings: How close to theand thereby potentially provide the best transmitter wire can I park the car? Canresolution of near-surface layers. In the Niels B. Christensen the car be inside the transmitter loop?autumn of 1990 I went to Canada to take Professor Emeritus How far can I move the receiver coila closer look, and in 1991 we bought it.Department of Earth Sciencesfrom the centre of the transmitter loop Aarhus Universitybefore it has an effect? How sloppy canAfter the necessary initial exercises in the nbc@geo.au.dk I be in laying out the square 4040 m2forest, we began to make rather small transmitter loop. Etc., etc.Does theseries of measurements in the areas Scene 2 transmitter display show the correctaround Aarhus, but fairly soon we got current value, and is the metre linear?involved in major mapping campaignsin which the transient electromagneticThere is an endless list of issues to bewith the Water Authorities of Aarhus and method makes its entry in Denmark, andtested when you get a new instrument,Aarhus County which was responsible buried valleys becomes a household term. and by and large I spend every day forfor administering natural resources: raw two weeks in the forest. Not bad, really. Imaterials like gravel and clays and water. like the place. Through the first campaigns, we realised In the forest that we had found precisely the data type So - we succeeded! We did manage to getthat made it possible to map the buried For the umpteenth time I get up and walka transient instrument! valley structures in Eastern Jutland that to the car, a Toyota Hiace, the most recentcompletely controlled the hydrogeology. acquisition of the Department for fieldEvery year since I came back fromDuring and after the latest glaciation, use. I get into the van, start the engine,Berkeley in 1987, I made applications tothe buried valleys were eroded out in drive a bit back and forth until it is 1 mthe National Research Council for moneyheavy Tertiary clays and then filled with closer to the transmitter loop. I stop theto buy a transient instrument to explorea variety of Quaternary materials, and engine, get out, measure the distanceits possibilities and limitations in relationpresently they were completely obscured between the wire and the car and make ato hydrogeological investigations, butby the Quaternary landscape at the note about it. Then I walk to the receiverin vain. As a newly appointed Associatesurface. In these buried valleys thick sand box of the transient instrument and forProfessor I didnt have the clout to carryformations were found which constituted the umpteenth-plus-one time I pusha project of that magnitude, at least thatthe best aquifers.the button that starts a new measuringis what they seemed to think. However, sequence. Sometimes the thought strikesin 1991, our Department joined a groupThe transient method permitted us me that if someone has been watchingfrom the Technical University of Denmarkto map the depth to the bottom of 31 PREVIEW APRIL 2022'