I'm fairly new to R so I'd like to apollogize in advance for eventually not choosing the best words to explain my issue.

My problem is that I'd like to create a subset out of a dataset (old) which has several colums. So far no problem... 

My subset should start when the value (x) in one of the colums reaches its highest point; and stop right after x droppend down again to its lowest point.
Then create a new dataset (new) with this subset of the data (old).

As there are multiple positions in my original dataset (old) where the value x behaves as descibed above I'd like to have a new dataset (new1, new2, new....) for every subset I create.

I hope a was clear in what I'd like to say. If there is more information needed, I'm happy to provide it.

Thanks a lot for your help.