Sediment & Rock types

Limestone is usually found in horizontal beds formed from lithified sediments consisting of mostly calcium carbonate.  Limestone beds are often interrupted by shale layers.   Limestone can vary from being soft and brittle to very hard and dense depending on the amount of clay or sand.
Fort Worth Limestone	Edwards Limestone [+]	Fort Worth Limestone
Rock Hill Ls.	Jacksboro Ls.	Jacksboro Ls.

Chalk is composed mostly of the calcareous skeletons of various marine micro-organisms.  The Austin Chalk below may not be a pure chalk.
Austin chalk	Austin chalk	Austin chalk

Shale is a general term for clay or silt deposits that are laminated (thin layers) and fissile (split easily).   Shale that has been exposed to weathering has a melted appearance.  Shale is often interrupted with beds of limestone.
Grayson shale	Eagle Ford shale
Placid shale [+]	Mingus Shale (bottom) [+]	Winchell Ls. (shale)

Mudstone / Claystone is a general term for consolidated mud or clay that is NOT laminated.   It maybe lithified or not.
Pawpaw Formation	Pawpaw Formation	Pawpaw Formation
Weno Formation

Sandstone is simply compacted and compressed sand that was deposited off or near shorelines as sandbars (shoals) and along shorelines as beaches and sand dunes further inland.  The massive fine-grained sandstone layers of "Pennsylvanian" age in north Texas are sourced from the erosion of ancient mountains in north Texas.
Paluxy Formation	Paluxy Formation	Woodbine Formation
Graham Formation [+]	Brazos River Fm.   [+]	??
Archer City Formation Montague Co., TX	Archer City Formation Montague Co., TX	Archer City Formation Montague Co., TX

Marl is rock that contains a large variable amounts of clay or lime mud.
Walnut Clay Formation	Walnut Clay Formation
Duck Creek Formation	Duck Creek Formation	Duck Creek Formation

Conglomerate (or alluvium) is rocks and sands that have been eroded and compacted in a non-marine setting such as river systems.
Pleistocene age alluvium Tarrant Co., TX	Lower Cretaceous age alluvium? [+] Montague Co., TX

Paleosols are fossil soils.  They are usually windblown deposits and can represent anything from arid areas to wetland areas.  The fossils found in paleosols are usually terrestrial in nature.
Permian age paleosols	Permian age paleosols	Cretaceous age paleosols
Paleosols or mud flats? Montague Co., TX	Paleosols Tarrant Co., TX	Paleosols Tarrant Co., TX

Miscellaneous or interesting strata.
Tarrant Co., TX	Tarrant Co., TX	Tarrant Co., TX