It is one of few noticeable pre-Cenozoic calderas, and its formation is associated to a period of crustal thinning that followed the Acadian orogeny in the northern Appalachian Mountains.

[4] The caldera is bounded to the east and west by fused Ordovician to Silurian turbiditic metasedimentary rocks of the local Digdeguash and Flume Ridge geological formations.

[4] Late Silurian to Devonian granitic rocks of the Saint George Batholith bound part of the southern margin of the caldera.

Rocks within the summit itself date back to the Upper Devonian, and show multiple fill sequences late in its history.

The positive early results have created great interest for gold-finding efforts, and the Mount Meager massif has proven to be an ideal candidate.

Gold quartz breccias and veins cut the McDougall Brook Microgranite and its volcanic wall-rock, while molybdenum-bismuth-tungsten and later polymetallic mineralization are related to the multiphase Mount Pleasant Granite.

[4] The Intercaldera Sequence comprises formations that crop out from overlying flows in triangularly shaped area, and includes thick volcanic ash (tuff), thick breccia layers, and intermediate to felsic igneous rocks that tend to intrude the above layers and are typically located along caldera margin faults.

The late Caldera-Fill Sequence contains rocks that are similar to those of the outflows of the other, older layers, and comprises two formations and two relatively minor intrusive lava flows.

The stratigraphic subdivision is supported by geochemical and mineralogical analyses, which indicate that the basaltic rocks are mantle-derived and have, unusually, relatively intraplate (or hotspot) type chemical affinities.

The relatively rare, more felsic flow units, are thought to have originated from high-end crystallization inside the magma chamber.

There are two types of rock associated with the basalt, conglomerate ranging in particle size from small pebbles to cobbles, and lithic lapilli tuff (well-worn, consolidated volcanic ash).

It can be found exposed in a limited region, encompassing the flank of the Hoyt Station basalt, colored light yellow in the diagram at right; it also peeks out closer to the volcano twice.

The Carrow formation is a predominantly fine-grained redbed (consisting of typically red sedimentary rocks) unit that has a grade ranging from pebbles and cobble in conglomerate at the base to mudstone laced with calcrete at the top.

[4] The lower part of the formation consists of unwelded and highly compacted lapilli tuff with abundant amounts of pumice fragments.

[4] The sedimentary breccia is dominated by pebble to boulder size angular metasedimentary stratas, and a few crystal tuff layers that contain about 1% biotite, the only such high amount of a typically trace mineral outside of Rothea formation in the Extracaldera sequence.

The exposed portion of the flows loosely flank the slopes of the volcano on the left and right, and are represented by bright orange on the map.

The exposed part of this layer is located around the southern base of the main caldera, and is colored ochre (light orange) on the diagram.

"[4] The Mount Pleasant Porphyry formation occurs as dykes and small rock areas that have been associated with local breccia.

When the mine was last producing - 1983 to 1985 - tungsten ore was regularly transported through Saint John by means of a provincial highway for shipment to Europe.

Electricity is provided by the New Brunswick transmission grid and water from a pump house located on the nearby Piskahegan River.

[1] On September 25, 2005, the Society of Economic Geologists hosted a small field trip to the caldera and the nearby Mount Pleasant Mine and Clarence stream deposit.

[8] On June 25, 2008, Geodex Minerals Ltd., a gold venture firm, announced the results of a 2007 - early 2008 diamond drilling program on the west side of Mount Pleasant.

Along with the development of the Sisson Brook tungsten-molybdenum-copper project north of Fredericton, the area surrounding the former Mount Pleasant mine has been a major focus of the company.

[6] In June 2011, the owners moved their corporate offices from Toronto to Fredericton with the intent of refocusing efforts onto getting the mine running again by 2012.