2. A [geologic map] of the collecting area if one is available. The list of publications of the Bureau of Economic Geology should be consulted to see if a geologic report or map of the area has been published. This list may be obtained without charge from the Bureau of Economic Geology, The University of Texas, Austin 12, Texas.
3. The [geologic map] of Texas. Although a geologic map of Texas is included in this publication ([Pl. 10]), the scale is so small that its use is somewhat limited. For more detailed work a larger geologic map in color (scale: 1 inch = 31.56 miles) may be ordered from the Bureau. The sale price is 25 cents.
4. A compass for more accurate location of collecting localities.
5. Adhesive or masking tape. The locality information can be written on the tape and applied directly to the specimen.
6. Paper labels (about 3×5 inches). A properly completed label should be placed inside each bag of material.
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.