échantillons de carottes

09:29 Sep 16, 2016 

Thanks Chris - good explanation!

09:01 Sep 16, 2016 

Given that "au droit de" may indeed mean "at right angles to", then it does make more sense. Imagine your long thin core sample, in which there may be many alternating layers of different clays etc. Each of these layers is like a disc, but precise information about the layer can only be obtained by taking a further (smaller) sample from within the disc itself, ie. by drilling in at right angles to the axis of the core sample. I take "ses" to refer to "le site".

08:18 Sep 16, 2016 

Thank you to all for your suggestions and comments. There are diagrams but nothing that helps to understand this really. There is a similar phrase later on: "La description visuelle des couches rencontrées au droit du sondage carotté réalisé au rond-point X est la suivante:"
Good point cchat about ses vs ces. I hadn't even thought of that and you are probably right! I also think that "perpendicular to" is correct. Maybe it means the core samples taken perpendicular to the sample area.

21:04 Sep 15, 2016 

I think au droit de is perpendicular to, in which case there is no tautology involved, but diagrams or figures really would be useful.

20:36 Sep 15, 2016 

The alternating characteristics can be seen in the core samples taken immediately by (attention au sens de "au droit de...") the sampled zone.
This needs a bit of reflection, and more context and/or diagrams in the text might help. A typical core sample might be, say, 1m long, but within that one core there might be dozens of different layers, each reflecting a different meteorological or geological event. This is usually the case with cores from, say, ice, trees or stalagmites.
My simple-minded interpretation is that the author is guilty of tautology since where else would a core sample come from if not from where the cores have been drilled? Unless, of course, the text has provided other information that we cannot see.

19:59 Sep 15, 2016 

I would say the difference here is between two sets of cores: samples from cores perpendicular to the other drilling survey. Also, is it "ses" or "ces" horizons ?

19:49 Sep 15, 2016 

carroting samples?