cross-bedded strata

basin-shaped strata

coal-storing strata

COMPLEX STRATA

Clay Strata

Continental Strata

Complicated Strata

AQUIFER STRATA

coal and strata combination

Cross Strata Pollution

Coal and Strata Correlation

Cretaceous strata

Carboniferous strata

Deep Burial Strata

belt of folded strata

ARCH OF SPANNING STRATA

CHERTY STRATA

CORRELATION OF STRATA

Age of strata

Cobble and Sand Strata