google sheetsgoogle-sheets-charts
I can approximate a stacked time-series plot using the Combo chart option in Google Sheets:
But it's not quite a "real" time series plot because the temporal gaps are not represented. Compare to this Scatter chart based on the same dataset:
Can I have the best of both worlds: a stacked scatter plot that uses X-axis values as timestamps, not labels?
My understanding of your requirement is as below, though this does not apply your sample data:
The layout of the left four columns is required - in effect I have substituted:
10 100
30 110
60 150
80 180
for your sample data in the OP.
I selected the data area, Charts, Charts, Line and checked both Use row 1 as headers and Use column A as labels. This ended up with the appearance of a scatter plot but in Advanced edit..., Customise, Features this, oddly, was fixed by checking Plot null values.
The colours, datapoints etc were customised for the image.
Instead of using a Line chart use the Time Line Chart, named as Annotated time line in Chart types - Google Docs editors Help. The look and feel of this chart was not updated yet, but it still works and do a great job handling date-time labels for the horizontal axis.
Best Answer
More of a workaround than answer.. but manually inserting empty rows (with dates) will pad the X-axis such that gaps are rendered:
Of course this requires modifying the data set, and also the dates are still treated as labels.