The timescale shows the units Eonothem, Erathem, Period, Epoch and Stage. It shows the begin of every period and if it is a GSSP. The timescale can be scrolled up and down if it does not fit on the screen. The view can be changed to fit the height of the display. Additionally, there is a true to scale option which sets the height of all periods according to its duration. You can select a period by touching it. Then, only the selected period and the subsequent periods are shown.
With the plus button it is possible to add a column with the more detailed unit at the right. The minus button removes the rightmost column. By sliding left or right, the view can be moved towards the more detailed or more coarse units. There is also a search function which highlights the desired period.
The App does not require an internet connection and does not need any permissions on your device.