The sedimentary rock record is significantly older than what we see on Earth -Michael Thorpe

This LPI is about Curiosity in Gale crater, not Percy in Jezero crater. However, they are both Hesperian environments. Gale was picked to be a slam-dunk sure-thing, late-era yet wet spot; Jezero is supposed to have more sedimentary action going on, and so far does.

Most of these slides are not so high-brow that someone only loosely familiar with the terminology would struggle to follow, but the first half of the LPI is building an argument. So if the early slides seem confusing, skip ahead, you aren't missing much.

What's happening is that clays tell you a lot. Clays tell you about weather, and wetness. The speaker is seeing where clays had time to form, and where they did not. And the contrast is telling. Mars is naturally porous, clays are denser and take time to make. So, among other things, you can measure how long, and how much of a part of Mars was "habitable" by observing clay deposits.

• I like this slide at 5:30 so I just want to mark it. Any time I can reference a good time-scale helps me personally.
• The slide at 22:50 really brings the LPI together. All the slides after are thematically in line as it is a very well constructed argument the speaker is making.
• Final thoughts at 40:00

The story of Gale crater is:

1. There was a Hesperian patch of Mars.
2. A crater-maker hit it.
3. The crater was now hot.
4. Some water flowed into it, cutting a short and deep canyon.
5. Ice-cap over that water, and some groundwater flows.
6. The water makes water-minerals.
7. The water leaves.
8. The water-minerals dry out.
9. Wind goes over the crater rim, picks water-mineral dust up from one side, and makes a mountain of it on the other.
10. The dust hardens into Mt Sharpe.
11. Curiosity goes to look at it.
12. It's still a crater that whole time.

So the fact is that Gale crater was never a good candidate to find "life", but it was highly likely to benchmark climate chemistry. And it did, this speaker is actively doing exactly that. The volumes and compounds of clay in this closed environment is now a usable measuring stick to compare against less controlled environments. Like Jezero.