The Carrington event lasted about 2 weeks. How much silt is deposited in that time?
In 2013, they published a report[0] considering the effects of solar storm risk to the North American electric grid.
tldr; it’s all about the transformers
[0] - https://assets.lloyds.com/assets/pdf-solar-storm-risk-to-the...
We've developed a fairly decent record of events back to 14,000 years ago
Look up 'Miyake events'
This keeps getting more interesting!
> Six diverse historical occurrences, from archaeological sites to natural disasters, have thus been dated to a specific year, using Miyake events as benchmarks and counting tree rings. For example, wooden houses in the Viking site at L'Anse aux Meadows in Newfoundland were dated by finding the 993 CE Miyake event and then counting tree rings, which showed that the wood is from a tree felled in 1021 CE.[
> At present, five significant events are known (7176 BCE, 5259 BCE, 660 BCE, 774 CE, 993 CE)
Seems like the Carrington event wasn't strong enough to be considered a Miyake event.
This method has been used to identify the reversal of the magnetic pole. [1]
Generally tho, such solar storm lasts for way too short amount of time to leave permanent evidence in the rock layers. However, I believe they have studied deviations in tree trunk rings.
If we wanted answers to that, I think we could inspect chunks of iron containing mudstone deposited anytime in the past few million years. By looking at the magnetic alignment of iron particulates, you will learn the magnetic field when the particle was laid down. With particles being so small, it seems likely one could reconstruct 5 minutely magnetic field angle, albeit with a big linearity error on the time axis due to the uncertainty in rate of silt deposits.
However, such a measurement should still give a good estimate of the frequency and magnitude of geomagnetic storms.