Find max and minimum values in a section of a column, then do the same in next section.

VBA

Sub test()
    Dim myArea As Range
    Columns("b:c").NumberFormat = "yyyy-mm-dd hh:mm"
    [b1:c1] = [{"min","max"}]
    For Each myArea In Range("a2", Range("a" & Rows.Count).End(xlUp)).SpecialCells(2).Areas
        myArea(1, 2).Resize(, 2).Value = Array(Evaluate("min(" & myArea.Address & "+0)"), Evaluate("max(" & myArea.Address & "+0)"))
    Next
End Sub