Lookup Next Occurrence and Mark Halfway Mark with "Mark"

Hi Excel Wizards, I need help please -

I'm trying to look at the Lows in column B and put a "Mark" in column C where the halfway mark is between 2 Lows, *if that next low is less than 30 data points off (if its more than 30 data points, we want a "Mark" 10 days prior to that second low). I'm happy if this takes more columns to achieve because I've tried vlookups, offsets and I cant manage to wrap my head around how to do this?

I've attached a spreadsheet to see what I'm trying to do - the first "Mark" shows up in column C in cell C36 because the second "Low" is greater than 30 data points away, so we put a mark 10 data points above where that second low occurred.

Any help would greatly be appreciated, thank you all!

Thanks Bo_Ry, is it possible to do this in reverse too? Like would I be able to do the same thing but look from bottom to top - but this time if the next Low above the previous low is more than 30 spots away, I would just "mark" 10 spots below that low above?
Reason I ask is that I thuoght I'd be able to take what youve done and figure it out how to adapt, but it's more functions in there than I know how to use
Thank again Bo_Ry

Thank you so much Bo_Ry! Solved - great help