peperite

The resulting mix of sediment and lava is called a peperite.

Peperite occurs where they flowed into Old Red Sandstone lakes.

Recognition of peperite is important in establishing broad contemporaneity of magmatism and sedimentation.

Devitrified obsidian and other volcanic glasses typically develop graphic textures; peperite is a typical rock formed by this process.

A Peperite is a sedimentary rock that contains fragments of igneous material and is formed when magma comes into contact with wet sediments.

When magma comes into contact with wet sediment several processes combine to produce the mixture of sedimentary and igneous clasts which is characteristic of a peperite.

The unlithified ash was swept into the shrinkage fractures, and, where the downward-propagating fractures intersected one another, basalt fragments were detached to form in situ peperite.

At an occurrence of peperite discovered recently among late Paleozoic island-arc deposits in the northern Sierra Nevada, it is possible to reconstruct the peperite-forming process largely from field observations alone.

Usually consists of glassy fragments of igneous rock and some sedimentary rock", while White (2000) defines peperite as "a genetic term applied to a rock formed essentially in situ by disintegration of magma intruding and mingling with unconsolidated or poorly consolidated, typically wet sediments.

So, I got my start on very old volcanism, but even in these 400 million+ year-old rocks, I saw some great volcanic features, including a gorgeous peperite, accetionary lapilli and rhyolite domes (in the unit above the Vinalhaven Diabase) ... and that's not even the most famous geologic feature on the island.