Unlike heat-bonded geotextiles, needle-punched geotextiles, both continuous filament
and staple fiber, of various thicknesses have similar cross-sections. This can be
seen by comparing photomicrographs of two needle-punched, continuous filament geotextiles C1
(Figure 4a) and C3 (Figure 11). The only difference between nonwoven, and
mechanically bonded geotextiles of various thicknesses (both continuous filament and
staple fiber) is the pore length through which a particle must travel.