That they are thin and tabular seems to be obvious, but a capa is a layer. I don't see why we need to complicate our lives by calling it anything else...

PDF] blank memo
File Format: PDF/Adobe Acrobat - View as HTML
forms: irregular masses, such as isolated nodules strewn through the rock; or as
thin tabular layers filling cracks,. be it vertical, horizontal or oblique. ...
www.slough.gov.uk/LocalEnvironment/ contaminated-land.pdf

[PDF] Joint spacing and distribution in deformation band shear zones
File Format: PDF/Adobe Acrobat
be described as thin, tabular layers of strong material. bounded by relatively
weaker sandstone layers, and in. this sense they present a layered mechanical ...
journals.cambridge.org/article_S0016756802007082


--------------------------------------------------
Note added at 17 hrs 24 mins (2005-07-28 08:35:56 GMT)
--------------------------------------------------

In defence of my literal translation, I would just like to point out that it does not say bancos tabulares (i.e. beds) (which, I agree, is more common than layers) and also that the terms bed and stratum are not synonymous.

HTH (it\'s all fascinating stuff!)