WHERE TO LOOK
Knowing where to look for fossils is a very important part of [fossil] collecting. It has already been pointed out that igneous and metamorphic rocks are not likely to be [fossiliferous], but that most fossils are found in marine sedimentary rocks. These sediments were deposited under conditions that were favorable for organisms during life and which facilitated preservation after death. Limestones, limy shales, and certain types of sandstones are typically deposited under such conditions.
One should look particularly for areas where rocks formed from marine sediments lie relatively flat and have not been greatly disturbed by heat, pressure, and other physical or chemical changes. If the rocks appear to have undergone considerable folding and fracturing, there is great likelihood that any fossils that were present have been destroyed or damaged by this action.
Quarries are good places to look but one should be sure to obtain permission before entering. [Rock] exposures in quarries are rather fresh but have undergone some weathering. Quarries have been opened in many of the limestone formations of Texas, and large numbers of fine specimens have been collected in some of these excavations. Certain Lower [Cretaceous] limestones are useful for road metal, building stone, or in the manufacture of portland cement, and extensive quarrying has been undertaken in the Edwards Plateau region of Texas ([Pl. 9]). Bones and petrified wood are frequently found in sand and gravel quarries in many parts of the State.
Particular attention should be given to all railroad and highway cuts as rocks exposed in this way are usually still in their original position and are fairly well weathered. Cuts made by recent construction are usually more productive after they have undergone a [period] of weathering as this helps to separate the fossils from their enclosing rocks.
Gullies, canyons, and stream beds are also good places to examine. These areas are continually subjected to the processes of erosion or stream action, and new material is uncovered year after year.
If there are abandoned coal mines nearby, the dumps of waste [rock] around the mine shafts could be checked. A careful examination of such waste may reveal fine specimens of well-preserved plant fossils.
Coal has been mined in several parts of Texas, and abandoned shafts or dumps are still present in some counties. The bituminous coals of Texas are predominantly [Pennsylvanian] in age, and mining has been carried on in the following counties: Eastland, Erath, Jack, Palo Pinto, Parker, Wise, Young.