a feeder pipe below Lopolith: concordant body with roughly flat top and a shallow convex base, may have a feeder dike or pipe below Phacolith: a concordant lens-shaped pluton that typically occupies the crest of an anticline or trough of a syncline Volcanic pipe or volcanic neck: tubular, roughly vertical body that may have been a feeder vent for a volcano Sill: a relatively thin tabular concordant body intruded along bedding planes Stock: a smaller irregular discordant intrusive Boss: a small stock See also Ellicott City Granodiorite Guilford Quartz Monzonite Pluton emplacement Norbeck Intrusive Suite Subvolcanic rock Tuolumne Intrusive Suite Volcanic rock Woodstock Quartz Monzonite References Petrology Rocks