What da heck is a volcanic neck?

Answer 1

Volcanic necks consist of plutonic rock formed during eruptions. Plutonic rocks actually cool below the surface, so they have more time to form stronger bonds and as such last longer than the ejected material.

Imagine a nearly flat surface as the volcano erupts the first time. The ground is pushed up as the magma rises to the surface. Rock is pretty hard, so typically magma is only ejected in relatively small areas (caldera forming eruptions are the exception). As it does this, it forms a tube, of sorts, which allows the magma to flow upward easier and the end result, after numerous eruptions, is a mountain.

While the volcanic rock (ash, glass, etc.) forms the outer slopes of the newly formed mountain, the stronger rock lies inside the slopes, forming the neck.

Fast forward a few million years: Erosion has taken place, removing the less resistant rock away, and leaving the volcanic neck, renamed a butte, behind.

Because volcanic necks have a lot of magma flowing through them, they can be a hodgepodge of different minerals, such as diamonds, emeralds, etc, in a kimberlite matrix.

Answer 2

A volcanic neck is a column of solidified lava that once filled the throat of an extinct volcano. Over time, the surrounding softer rock erodes, leaving behind the more resistant volcanic neck as a prominent landform. It often appears as a steep-sided formation, sometimes with a crater at the top.