Mt. Cecilia is a laccolith. Magma intruded between layers of sedimentary rock, without disrupting the layers themselves, so that the overlying stratum was forced upward, giving the laccolith a dome form. It is plano-convex in shape, and flattened at the stratification joint, i.e. the upper and lower limit of a layer; these limits often consist of erosion surfaces or surfaces where sediment did not deposit. Magmatic rocks, namely latite, are the first we meet along the trail: latite is a volcanic rock which mostly contains feldspars. Latite products are the last ones in the Euganian volcanic process; this means that magma composition progressively becomes less acid.
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