The amount of time that nuclear waste can remain dangerous is a staggering length of time. To compare this to the time gone by since the supercontinent Pangea existed and the age of the Earth, we can use ratios or percentages.
The supercontinent Pangea existed around 335 million years ago, and the Earth is estimated to be around 4.54 billion years old. Therefore, the ratio of the time since Pangea to the age of the Earth is:
Time since Pangea / Age of Earth = 335,000,000 / 4,540,000,000
Time since Pangea / Age of Earth ≈ 0.0738 or 7.38%
In comparison, the length of time that nuclear waste can remain dangerous is at least 250,000 years. Therefore, the ratio of the time nuclear waste can remain dangerous to the age of the Earth is:
Time nuclear waste can remain dangerous / Age of Earth = 250,000 / 4,540,000,000
Time nuclear waste can remain dangerous / Age of Earth ≈ 0.000055 or 0.0055%
This shows that the length of time that nuclear waste can remain dangerous is a tiny fraction of the time that has passed since the Earth was formed, but still an incredibly long time compared to human lifetimes or even the entirety of recorded human history.