It is the second youngest of four overlapping volcanic cones which together form the most voluminous stratovolcano in the Cascade Range.

Shastina has a topographic prominence of over 450 ft (137 m) above the saddle connecting it with Shasta and easily exceeds the typical mountaineering standard of 300 feet (91 m) for a peak to qualify as an independent summit, yet most lists of Cascade volcanoes omit it nonetheless.

[3] Shastina has the general form of a smooth-sided cone truncated by a one half-mile (0.8 km) diameter summit crater, but with several geological features which make it unique among other volcanoes in the Cascade Volcanic Arc.

The most prominent feature when seen from lowland viewpoints is Diller Canyon, a large cleft carved into the western flank by pyroclastic flows and since expanded by erosion.

Highest of all is an unnamed lake at over 11,960 ft (3,645 m) on the south side of the cinder cone which forms Shastina's true summit.