The shallow seas of the Cretaceous swarmed with invertebrate life; foraminifers (unicellular protozoans) in uncountable billions make up large parts of the chalky limestones. Mollusks, particularly clams like oysters and the heavy ribbed Inoceramus, and complexly sutured cephalopods, the ammonites, as well as the internal-shelled belemnoids (that look like cigars), were most numerous among larger marine animals. Reef builders in southwestern New Mexico were the peculiarly corallike clams, the rudistids. Widespread warm humid climates seem to have prevailed throughout the state during most of the Cretaceous. LANDSCAPES AND MINERAL RESOURCES Thus as the Cretaceous seas withdrew from New Mexico, the Cenozoic Era dawned, and never again have marine waters shaped the landscapes. The rocks, Precambrian, Paleozoic, Mesozoic, and Cenozoic, and their ancient movements determine New Mexico’s spectacular landscapes. They tell tales of the endless war between erosion and hard rock, show the deposition of sediments, their uplift, and their eventual destruction. The result is striking scenery—volcanic mountains, as Mount Taylor, Sierra Blanca, Valle Grande—fresh lava flows near Carrizozo and Grants—volcanic necks like Shiprock and Cabezon—White Sands, the work of the wind—El Morro, Enchanted Mesa, Acoma, and badlands near Santa Fe, the result of weathering and erosion—great fault-line escarpments of the Sandia, Manzano, San Andres, and Sacramento mountains—the work of underground waters at Carlsbad Caverns. And man adds his erosive powers—the huge open-pit copper mine at Santa Rita and countless excavations for rock to build homes, to straighten highways. [Illustration: Figure 10. Make way for ’is lordship, the Dinosaur!] The sun can be harsh and hot, the rain sparse, the winter nights fierce cold. But within the rocks are natural resources undreamed of by the early Indians, almost untouched by the Spanish, and with potential beyond vision for the future. Water, being scarce, is one of the more important resources. With an average yearly precipitation of only fifteen inches, and more than half of the state receiving less than that average, water is a problem! Farming must depend upon irrigation, the water being drawn from streams or “mined” from underground “pools” where it had been accumulating for centuries.