Dear Mr. Silva,

I belong to an older age-group of geoscientists,starting my career during the mid-1970s, who mapped with hammer and hand lens in a foot-borne manner. For soil sciences you have the drill-stick/auger and your shovel/spade to dig a small trench or so. You had your topographic map on a plate hanging around on a cord, a rucksack for the samples and a field hat to do not turn into a “red-neck”. The process went on slowly but steadily and with each new sample and observation you extended your practical experience and widened your knowledge. In my study I copied my field data on my final map using pencils in black and in color. When the map was entirely colored the mapping job was done.

I also entered into the digital world with satellite images and design software via aerial images, stereoscope and supported by hand-held devices such as spectrometer, kappa-meter, PIMA etc.. for capturing digital data in the field and save it on my laptop. In the field camp or at home the same procedure took place but with the pencils replaced by the keyboard and the mouse.

H.G.Dill

Well,

The geological field measurements are still required for more accurate survey results in all geological branches.

Regards.

Earlier methodology for the preparation of geological and soil maps has been very clearly and in detail explained by Dr. Dill. Yes it used to be very difficult and time consuming, however it was 100% perfect. With the advent of remote sensing / digital era, the process of mapping has become less labour intensive, lesser time and economical. Many of the earlier in-assessible areas are now approached/covered/studied through remote sensing technique. However, the results obtained through remote sensing technique have to be validated through field checks/investigations/data. This means, the RS technique has to be considered as a first approximation, and also it has to be kept in mind this technique is not a replacement for field investigations.

Thank you Dear Harald G. Dill , Bayan Hussien and N B Narasimha Prasad . Your comments have been very helpful to me.

However, I would like to get a little more information if possible. How was possible to define the boundaries of a particular geological layer/formation? So, you mean the samples were collect around the boundaries?

Thank you in advance!

It is rather simple. Go down-slope, try and identify the first appearrance of a lithology or a soil type and mark this point in your topographic map, aerial or satellite image. If debris do not properly allow for that use your drill stick for clarification. In case of pedological or regolith mapping you should in any case use your devices which enable you to get an insight into the soil or weathering profile.

H.G.Dill

Okay, make more sense to me now. Thank you so much Harald G. Dill . Well appreciated here.

Dear Patrik,

We belong to the technology era and satellite surveys and thinking for work as a researcher without satellite data, softwares, and GIS data is unbelievable. But it doesn't mean that previous works were not precise. I have seen so many works done before recent era but very precise and with the highest accuracy. Their works were based on field observations and direct samplings, analyses, and interpretations. It makes the geology works perfect. The data obtained from satellite images help us and accelerate our work. It is awesome and makes our work attractive and trustable but in many new published researches I have seen that most of researchers do their work just according to the obtained data from satellites without enough field work and required validations. In fact, unfortunately technology has made scientists lazy :).

Regards,

Rahim

Thank you dear Rahim Masoumi . I agree with you.

However, for me it was just a curiosity.

PS

I led a team of geologists who produced a series of 1:25,000 geological maps of the Broken Hill high grade metamorphic area, Australia. All of the work was done before GPS and done more efficiently than it could be by relying on GPS. We mapped on transparent plastic overlays on aerial photographs at a scale of 1:12,000, then transferred the information to corrected base maps at the same scale. The nature of the rocks is such that mapping by remote sensing is useless. About half of the effort in mapping was in locating yourself on the aerial photograph. We walked the boundaries of most of the rock units, and traversed the larger units of metasediment, recording the variations across strike. Relying on GPS in such an area would have been so time consuming that we would never have finished.

There is no (economic) geology without field geology

H.G.Dill

During the Victorian era in the UK the Ordnance Survey began detailed 1:10000 scale (equivalent of old imperial measure) mapping of the whole of the British Isles. This provided the Geol. Survey of Great Britain with highly accurate maps for plotting the geology. The work done by both the Geol. Survey and the Ordnance Survey was done on foot and was amazingly accurate. The finest example of the work of the Geol. Survey was that done in the NW of Scotland. The surveyors included Ben Peach, John Horne, Read, Flett, Clough and others. They walked over every inch mapping all geol. boundaries, strike and dip, took rock samples for further study in the lab. Personally I am in awe of their work; their accuracy has helped me to find small but vital outcrops in the most remote of places. The Memoir of the North West Highlands of Scotland by the Geol. Survey is a must to read if you really want to find out how geol. surveying was done, yes even before aerial photography was available. Its advent in the 20th century was a great boon, but still requires feet on the ground to check structures and rocks out. Hope this helps Patrik

George Strachan

Patrik,

The full reference to the above is

Peach B.N., Horne J., Gunn W., Clough C.T., Teall J.J.H. (1907) "The Geological Structure of the North-West Highlands of Scotland", HM Stationery Glasgow.

Another that worked with these redoutable geologists was Charles Lapworth of whom a very fine chapter is written in - "The Highland Controversy", by David Oldroyd, (1990), Chicago Press. In Ch.8 (p.217-265) is laid out the brilliant fieldwork undertaken by Lapworth in his study of the geology and structures of the Palaeozoic strata found at Dobb's Linn in the Scottish Borders in the 1870s. He used graptolites to relatively date the strata and relate faulted strata across the fault.

I must also mention the great work of G.K.Gilbert and John Powell in North America in the 1870s on to the end of the century. Powell surveyed the Grand Canyon by canoeing down its length - no mean feat; and Gilbert surveyed an area to the north of the Canyon (his work is summarised in "The Geology of the Henry Mountains"

Even with aerial photography and satellite imagery to identify macro-structures, these men elucidated the geology in amazing detail. And still today we need to go out in the field to check what modern technology tells us

George Strachan

Dear all: Yes, geology was done in the field when no satellite imagery was available many decades ago. I belong also to the "pre-digital" era, since I entered the Geology Department ar C.U.V. in 1976. In my country, Venezuela, when I was a student and in the beginning years of my career, many places didn't even had topographic maps in low scales, and some still haven't! Most of these remote places were accessible only through creeks and rivers, no roads whatsoever, not even dirt roads! All one had were 1:100.000 or larger scale maps of part of the territory. So one had to "draw" the creeks and rivers using topographic equipment, beginning with some reference point, usually a church bell-house in small towns. And then put the lithologic contacts, structures and the like on the newly drawn map!

I don't agree when somebody says that field mapping was perfect, or 100% perfect. There is nothing perfect in geology, to say so is to be really naive ir extremely optimistic! No matter how good outcrops one might find, no matter how well the sampling is done, no matter how sophisticated equipment is used for chemical, isotope, and radioactive analysis, we never will be able to describe 100% of the geological events happened in the past. It is simply impossible! We can give educated propositions of geological history, but not the 100% of the facts. Let's be a bit modest, right?

Moreover, a great part of geological history has been erased by that villain called erosion, so no continuous sequences exist anywhere. It is like a CSI crime scene where some intruder takes away valuable evidence from the site! In tropical countries mapping is very defective, since thick lateritic soils, heavy forests, and wide alluvial deposits cover most of the terrain. In mountainous areas all one can have is outcrops in creeks and rivers, and many of them are quite difficult for access, as they have falls, cataracts, rapids, and all sort of obstacles. Even road outcrops get quickly weathered and become useless after a few years! But, as I said before, and I always remind to my students at the beginning of each semester: even in the best outcrops you might find in Greenland, Canada, Siberia, and desertic areas, more than 70% of the geological history has been erased by the erosion villain! Regards, Sebastian.

I have the highest respect for Sebastián in carrying out field geology in South America. To have to first map the land surface before adding geological data is very time consuming and adds greatly to the work load.

As for me working in the Scottish Highlands, there is no fear of “red-neck” problems in our climate. All we have to endure is horizontal rain, sleet and snow and in summer/autumn the midges, which can drive even the most devoted field geologist to madness!

George Strachan

Exactly. I would tell my students to 'get mud on their boots', 'you are undressed without a hand lens', and 'autopsies are not done on a photo of the victim'.

Then there is the awe at looking at one lone fossil for the first time in 520 ma . . .

Technology helps, but it is not (yet?) the answer.

Thank you all for your comments and suggestions. Well appreciated here.

PS

Aerial photography, estructural geology, paleontology, geobotany. Extensive fieldwork.

La geomorfologia pre digital, tambien tuvo un rol protagónico es estudios de suelos. Un forma del terreno, esta muy correlacionada con el suelo, que la cubre. Saludos

Dear Patrick Silva,

To your question got a very beautiful responses from the previous responders. That is why I will mention a story of mine which happened in the time of MSC (1984-1986). writing. My diploma work tittle was:

"PG Volcanic rocs of Zlatna Basine... " In the zone was described Miocene andesites-rhyolite... Interesting was that all Volcanics rocks of the zone were considered Miocene age... So to separate these two ages Volcanic rocks it was a big challenge for me... But I had great luck in time of Mapping (as Prof Sebastian Grande and Prof.Harald G. Dill described down) I made a mistake 0.5 km and went out from the project are and found natural opening (It3-4 m long and 1.5 m high) in center of the opening was a basalt lava flow: under it was a sedimentary rock (conglomerate with few rounded rose-colored rhyolites and top of basaltic flow was greenish-white rhyolite... So immediately I knew how could separate PG volcanic rocks...

So from the mentioned example, you can understand well that geological and soils maps have remained the same important today too.

Regards,

Laszlo

The classical geological and soils mapping is direct contact with the studied are, when where you are "walking-climbing" it is telling you its secret!

Dear Laszlo: indeed, field mapping and description is real direct contact with nature, especially in tropical areas like Venezuela, with thick jungle cover with warm and humid weather, where one has to deal not only with hard climbs in creeks and ravines, but with all sort of bugs (mosquitoes of all kinds, scorpions, hairy worms), and of course, poisonous snakes of bothrops and crotalus species! (actually in many years of field work I've seldom seen poisonous snakes, they are night creatures, so during the day one usually sees boas and non-poisonous serpents). But, one wears high boots, and takes along a snake anti-venom kit, among other things! Nonetheless all the difficulties found, there's no substitute for this kind of field work in mountainous areas and the Precambrian Guiana Shield, and each new outcrop found, each new structure mapped, is a really satisfying and rewarding experience! Regards, Sebastián.

Dear Sebastián,

our Highland midgies pale into insignificance when on fieldwork. Even the one poisonous snake in Britain, the adder, was banned from the Gairloch area, my favourite geo. area, by Saint Maolrubha (or so the legend goes). Yes, nothing to replace the pleasure and satisfaction got in carrying out real fieldwork.

Kindest regards

George

"Was it done manually then digitisef?" In the beginning there was no such thing as digitising. The geologist gave the hand drawn map to a cartographer who scribed the map on plastic and delivered the plastic to the printer. In later days the geologist's jand drawn map was scanned and a cartographer drew the map in Arcview.

The answer is: Brain + Boots + "Bussola" (compass in my native language, Portuguese) + Board with topo maps + Bruises + Blood (some drops at least sometimes) = Best Geological Maps ever.

With tools like Brunton Compass, Geological Hammer, Lens and a Base Topographic Map/Sheet. A couple of pencil colours etc. for colouring polygons that used to check on ground for a particular litho-unit and so is with lines related to structures etc. Latter, in due course, they were either finalised with special pens like rotrings and further latter by way of digitisation using relevant softwares.

Best,

AK