Meaning of 'over' in "Over a period of about half an hour what remained...

[Klpno]

Hello everyone

I'd like to ask about the meaning of "over" in the following context:

Over a period of about half an hour what remained of the orb shapes started to spin around a center formed by a gray energy sphere, which did not have defined edges such as the orbs have. The orbs by this time appeared like ragged pieces of white cloth, as you can see in figure I-37.

Does "over" mean during/for, or does it mean "after a period of about half an hour had passed"?

[Alan]

Hi KLPNO,

'Over' in the sense to which you are referring does express one or two ideas. It has this sense of 'through/throughout' but at the same time it indicates a gradual process. Look at this: Over the last 12 months the British prime minister has undergone a complete change in fortunes. What this means is that during/for the last 12 months and also gradually the prime minister's popularity has dramatically changed. This covers the 12 month period from start to finish and hints at the process within that period.

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

[Klpno]

Thank you very much, Alan.