As an enterprise architect and former IT architect I’m often confronted with systems representations and it seems the only available metaphor is the layer with some subtle variations in the number of layers and the number of mandatory « bars » spanning the layers. So I came up with new variations with some fresh visual effects to help candying powerpoint presentations.
Architecture et structure 
I can tell you about a context where self-entitled architects seriously coined the phrase « vertical layers ». They are very serious about it. Serious, it surely is… from a more geological perspective!
Anyway, unless enterprise architecture happens to be something more than slideware, we will have to endure this kind of insults against the spirit.
When it comes to layers in architecture (whatever the kind of architecture), it raises the question of the methodological framework or « content framework » (to reuse the expression taken from TOGAF). Here, we have to be very careful and aware of the implications.
I tried to analyze the rules such a framework must obey (see: http://dvau-en.praxeme.info/?p=72). Certainly, it is something slightly different from a beautiful picture on a slide.
And, to link this post with the previous one on reality, we often mistake the picture for the reality, the slide for the framework, and even the framework for the reality.