En algunas partes del mundo, Bolivia por ejemplo, usan la expresión "canaleta" para referirse al cilindro testigo de la perforación.
La expresión usual es "canal", es decir muestra de canal.
Dicho corte a la muestra cilindrica de canal se hace longitudinalmente al buzamiento de la formación, no necesariamente perpendicular a la muestra de canal (es un cilindro), de tal manera de atravezar los estratos.
La muestra de canal es fundamental para determinar la geología de los estratos que se van atravezando.
De acuerdo al contexto no cabe otra posibilidad.

Muestra de canal = Channel sample.

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Note added at 8 hrs (2010-03-05 18:21:55 GMT)
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Core samples and channel samples are obtained by the same procedure.
In this context, petroleum prospecting, the prefered term being used is "muestra de canal"/channel sample, otherwise the author would have written "muestra testigo"/"core sample".

See uses of the term in the following web pages,

http://www.fortunegraphite.com/files/Download/AA 1-22 MINFIL...
In 1985, the company collected a channel sample across 2.0 metres of highly

http://link.aip.org/link/?JERTD2/126/112/1
More and more strict environmental regulations have forced the petroleum ... from each solid composite sample (pit A) or channel sample (pit B) three ...

http://www.ore-leave.com/baiasprie.html
a surface channel sample intersect of 12 metres true-width returned 5.17 g/t Au and was tested at 70 metres below the surface with drill ...

http://emg.geoscienceworld.org/cgi/content/full/14/1-4/31/T1
Canadian Institute of Mining, Metallurgy & Petroleum ... 10-m-long channel sample: 0.040% Ta2O5, 2.299% Cs2O, 0.372% Rb2O, 0.971% Li2O. ...

http://minfile.gov.bc.ca/report.aspx?f=PDF&r=Minfile_Detail....
A 30 centimetre channel sample assayed 33.6 grams per tonne gold, ...

http://linkinghub.elsevier.com/retrieve/pii/S001623619700164...
A standard channel sample represents the full thickness of a coal seam at the sample site ......

http://www.egoldfields.com/goldfields/uploads/press/Update22...
Samples from the underground and surface channel sample program were

http://www.platinumgroupmetals.net/about_platinum/glossary/
channel sample is a surface sample which has been collected by continuous

http://www.gippslandltd.com/quarterly/ASX Quarterly Apr - Ju...
Table 3: Um Shashoba prospect channel sample results ...

http://www.onepetro.org/google/Papers/SPE/eLibrary_Papers/sp...
cores at 90° to the well trajectory, or cutting a channel sample ...

http://blogs.wooeb.com/crwepick/BlogsList.aspx?m=1&y=2010
These high grade channel sample results are significant as Vein No. ...



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Note added at 8 hrs (2010-03-05 18:31:15 GMT)
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Do not worry, Gilmar. Mi first intention was to suggest "core samples" but then had some second thoughts about the Spanish use of the term.