Final answer:
The statement about Ashfall, Nebraska, being similar to African savannas millions of years ago is true. Savannas are grassy plains important to biodiversity and human history, characterized by warm temperatures, seasonal rainfall, and an array of wildlife.
Step-by-step explanation:
The statement that 'Ten million years ago, the area around Ashfall, Nebraska, held water holes within a savanna setting, a warm, flat grassland similar to some classic wildlife areas in Africa today' is true. The ancient savannas, much like modern African savannas, provided diverse and fertile habitats that supported a wide array of wildlife and were vital ecosystems for migrating and resident species. Savannas have historically been crucial environments supporting a vast diversity of life, from large grazing mammals such as wildebeests and zebras to the human societies that thrived along riverbanks like the Niger River.
Throughout history, savannas have been hotspots of biodiversity and human settlement. They are characterized by warm temperatures, seasonal rainfall, and an abundance of grasses with scattered trees—conditions that have fostered thriving communities of plants, animals, and humans over millennia. The description of savannas as grassy plains with scattered trees, receiving modest to substantial rainfall, and hosting a wide array of plant and animal life, matches the ecological conditions that were likely present around Ashfall, Nebraska, millions of years ago.