Molasses holocaust: The tank was filled with more than two million gallons...

[Ashish1354]

Long-time Boston residents still talk about the molasses flood that engulfed the city’s
north end on January 15, 1919. Many people were sitting near the Purity Distilling Corporation’sfifty foot high molasses tank enjoying the unseasonably warm day. The tank was filled with more than two million gallons of molasses—and it was about to burst apart.

or

Long-time Boston residents still talk about the molasses flood that engulfed the city’s
north end on January 15, 1919. Many people were sitting near the Purity Distilling Corporation’sfifty foot high molasses tank enjoying the unseasonably warm day. The tank was filled with over two million gallons of molasses and it was about to burst apart.

Between above two differently puntuated versions of same text which one is preferable and why?

[Alan]

Hi,

The use of the dash (-) in the first sentence is used for dramatic effect.

Alan
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English as a Second Language
You can read my ESL story Present Simple