Notes:C-horizons are glacial or post-glacial material in the Northeast.
From Soil Taxonomy:
C horizons or layers: Horizons or layers, excluding hard bedrock, that are little affected by pedogenic processes and lack the properties of O, A, E, or B horizons. Most are mineral layers. The material of C layers may be either like or unlike the material from which the solum has presumably formed. The C horizon may have been modified, even if there is no evidence of pedogenesis.
Included as C layers are sediment, saprolite, unconsolidated bedrock, and other geologic materials which are commonly noncemented and characterized by low or moderate excavation difficulty. Some soils form in material that is already highly weathered, and if such material does not meet the requirements for A, E, or B horizons, it is designated C. Changes not considered pedogenic are those not related to overlying horizons. Layers that contain accumulations of silica, carbonates, gypsum, or more soluble salts are included in C horizons, even if indurated. However, if an indurated layer is obviously affected by pedogenic processes, it is considered a B horizon.