These desks had the usual

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Here's another snippet from the same Roald Dahl passage. What's distinctive about this one?

These desks had the usual sloping wooden tops with a narrow flat strip at the far end where there was a groove to hold your pen and a small hole in the right-hand side in which the ink-well sat. 

Boy(1984)

This snippet is also about elaborate noun groups and lots of prepositional phrases.

It's a description of the components of a desk, so the prepositional phrases are all about clarifying where things are positioned and what they are for.

Here are a couple of examples that also use long prepositional phrases to describe the components of something:

The mountains made an impenetrable barrier with sheer black cliffs at the base from which rose a jagged curtain of icy peaks and a dark crown of storm clouds in which purple lightning twitched.

Master Abel had a peculiar set of glowing spears in a locked cabinet behind a secret bookshelf which held dozens of pamphlets about guerilla warfare and a three-volume encyclopedia on obscure treatments for magical burns and injuries.

Write your own description of the components of something. Aim to describe three components/things each with prepositional phrases expanding on the details.