tter half of the Paleozoic era, sediments rich in organic matter accumulated here when a shallow sea got cut off from the main oceans and evaporated off, leaving lots of dead critters and evaporites. These sediments eventually got buried and compressed, causing the oil and gas to form "pockets in permeable rock, surrounded by impermeable rocks so that they couldn't escape. There the fluid sits until someone pokes a hole (well) into the area and the contents rush out as the tremendous pressure is released. Other areas of Texas with notable petroleum sources include East Texas's Woodbine Formation (formed in the Late Cretaceous), much of the Gulf Coast and the Gulf itself, and various smaller pockets in South and South Central Texas.Coal may be overshadowed by petroleum in Texas, but it's still here. Pennsylvanian age bituminous coal was mined in North Central Texas in sizable quantities. Bituminous coal can also be found in Cretaceous age rocks in near Eagle Pass and in the Trans-Pecos region. But the major player in Texas coal is Lignite, even though it is a lower grade coal. The Texas lignite comes from vegetative material deposited around 50 million years ago in coastal lagoon type environments, near rivers and their deltas. The material was buried before it could decay, so it sat there and was buried under more and more sediments. The enormous weight of the sediments produced the heat and pressure required the turn the organic matter into coal. Helium is a non-petroleum gas that most people are fairly familiar with. But many people are surprised to learn that it is also a natural Texas resource. Helium is often found with natural gas produced by wells in the Panhandle. Helium is not just used to float blimps and balloons. It is classified as an inert gas and won't burn, making it ideal for activities like shielding in welding and a variety of scientific and medical uses. Rocks are also important Texas natural resources...
