Not mountains, but petrified Giant Trees
Giant trees that grew miles tall and some of the bases miles across. Here we have some pictures showing regular tree stumps next to Giant stumps.
Also these zoomed in samples of Cross-cut Sections from tree stumps look interesting.
@ZGoldenReport, that will be hard for most to wrap their head around.
Yet, this is when we had dragonflies with 3 foot wingspans.