Merging two time series in columns into one column

Hi,

I'm trying to merge two time series into one single time series.

For example, time series 1 starts in cell A2 (column A) and extends through cell A11 and time series two starts in cell B2 (column B) and extends through cell B11. I'm trying to merge these two time series into one time series such that the original cell A2 remains at A2 and the original cell B2 moves to cell A3, cell A3 moves to cell A4, cell B3 moves to cell A5. Is there a formula I can use to quickly do this? The entire time series spans over 3000+ data points. I've attached an example of what I'm trying to do.

Thank you very much for your help!