Various tectonic processes cause the uplift of mountains. Earthquakes may well be a byproduct, but are not really the cause.
I was breaking this down for someone who may not clearly understand.
Actually, the limestone sediment was formed in the marine environment, largely biogeneticly. In other words, the limestone (calcium carbonate) of the rock itself is produced by organisms.
Limestone is just decayed coral that has hardened over time. It has to be first out of the water to be limestone.
Although there may well be related subduction activity, tectonic uplift is not subduction.
I'm just speaking in generalities about the overall tectonic process that allows for mountains to come in to being. I'm just explaining how seashells can get on to a mountain, not writing a technical thesis on tectonics.
Obviously the implicit undertones were that seashells got there because of the Flood. I'm just clarifying for him other options he needs to consider before ruling out anything other than a worldwide flood.
"Fix reason firmly in her seat, and call to her tribunal every fact, every opinion. Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blindfolded fear." Thomas Jefferson