Q:

Writing "U-shaped" and "V-shaped" in novel

If you are describing a valley as U-shaped, what is the correct way to write that in a novel. 
U-shaped
U shaped
u shaped
u-shaped
"U" shaped
"U"-shaped
other variations?

A:

Many years ago, various prominent U.S. style guides used to recommend using gothic (sans serif) type in otherwise roman (serif) text to indicate a letter-as-shape letter, but I haven't seen this done in practice very often in recent years. In fact, as early as Words into Type, third edition (1974), style guides were already moving away from the gothic recommendation. Here is WiT's coverage of the topic:

When a letter is used to designate shape, tradition calls for a gothic letter, but roman is now more often used. Italic is not satisfactory for this purpose.

[Examples:] a U-shaped tube, a great V of foam, an S-shaped cross section, a T-square

Indeed, the 1948 first edition of Words into Type says that "When a letter is used to designate shape, elegance calls for the use of a gothic letter," before conceding that, even then, "roman is more often used." You can see multiple instances of "U-shaped valley" and "V-shaped valley" handled in the old elegant way in J.B. Tyrell, "The Law of the Pay-streak in Placer Deposits," in Transactions of the Institution of Mining and Metallurgy, Twenty-First Session, 1911–1912 (1912).
The Chicago Manual of Style, fourteenth edition (1993) still seems interested in matching the form of the letter to the shape being described—sans serifs (or serifs) and all—while not fully endorsing making this the decisive consideration:

Letters as Shapes
6.90 Either roman or gothic (sans serif) letters may be used for indicating shape:

[Examples:] A V-shaped valley becomes U-shaped by glaciation.
an S curve, an A-frame

Sometimes a roman letter suggests a particular shape better than a gothic one:

[Example:] a steel I-beam

However, The Chicago Manual of Style, sixteenth edition (2010), essentially abandons the old preference altogether:

7.63. Letters as shapes. Letters that are used to represent shapes are capitalized and set in roman type. (an S curve, an L-shaped room). (Using a sans serif font in a serif context, as is sometimes done, does not necessarily aid comprehension and, unless the sans serif  perfectly complements the serif, tends to look clumsy.)

One constant through all of these discussions is the inclusion of a hyphen when the term in question is L-shaped, S-shaped, U-shaped, V-shaped, etc.

