Fig. 12.-- View of a sand prairie near Kilbourne, Mason County, showing a society of goat’s rue. The black-jack oak 
and black oak forest in the distance is second growth. 
in the sand areas of the Illinois River, chiefly those 
near Havana. 
8. TWIN CULVERT CAVE 
Twin Culvert Cave is located in the middle of 
the southwest quarter of section 17, T. 7 S., R. 2 W., 
about 2 miles southwest of Pearl, Pike County. The 
name is taken from the two large limestone overpass- 
es, fig. 13, that span a small stream, the bed of which 
at this place also forms a part of the county road to 
the southeast. The overpass or culvert on the south 
carries tracks of the Gulf Mobile and Ohio Railroad. 
The culvert on the north has become covered with 
brush. It was once part of a railroad trackway, now 
abandoned. The creek that flows through these cul- 
verts is small, but in periods of heavy rains it may 
rise 8 feet or more above the gravel stream bed. The 
cave is located between the two culverts, upslope on 
the west bank of the small stream, very close to the 
present railroad trackway. 
The slope on which the cave is found supports a 
deciduous forest containing such species as hard 
maple, white ash, black walnut, chinquapin oak, hop 
hornbeam, and shingle oak growing together. Some of 
the common shrubs are poison ivy, wild hydrangea, 
bladdernut, wafer ash, and buckthorn. Wild grapes and 
climbing bittersweet are common vines. Of the her- 
12 
baceous plants, fragile fern, clearweed, bedstraws, 
and violets occur very frequently. 
The bluff bordering the abandoned trackway on 
the west side of the creek has been altered by the 
removal of rock, possibly for the construction of the 
Fig. 13.-- Culverts constructed of local limestone 
near Pearl, Pike County. These culverts supply the name -- 
Twin Culvert Cave -- for the nearby cave. An infrequently 
used county road and a small stream share the culverts. 
