The Relief Canyon gold deposit in the Humboldt Range of western Nevada is a low-grade, high-tonnage orebody of Tertiary or younger age. The host rocks include limestones of the Triassic Cane Spring Formation, which are overlain by shales of the Triassic Grass Valley Formation. The rocks were folded and metamorphosed to greenschist grade during Jurassic and Cretaceous regional tectonic activity. Mesozoic thrusting may have occurred along the shale-limestone contact, but evidence has been obscured by later hydrothermal activity. The sedimentary rocks were nominally offset along several Late Tertiary normal faults related to uplift of the range.

Modern amphibians - the familiar frogs and salamanders of the Northern Hemisphere and the less well-known, elongate, and limbless caecilians of the Southern Hemisphere-appear as relatively minor components of the living fauna, although they actually outnumber the dominant mammals in terms of both numbers of species and individuals. In fact, the three modern amphibian groups are but relicts of a much larger radiation that occurred between 370 and 270 million years ago, when their ancestors dominated terrestrial and shallow water environments throughout the world. Of even greater significance, the early amphibians provided an evolutionary link between archaic fish and the ancestors of all more advanced terrestrial vertebrates: the reptiles, birds, and mammals. That is, they were our own <...>

The story of fishes through time is also the story of changing continents and climates, devastating mass extinctions and changing faunas and floras. The complete picture can be grasped only from a multifaceted approach, and this is why there are several sections here giving extra information for nonpalaeontologists. A glossary of complex or scientific terms is included in the back for ready reference. <...>

The evolutionary explosion of mammals at the beginning of the Cenozoic Era, which began 66 million years ago, is a key event in our distant origins, and it is one of the main topics in current biological and paleontological studies. Knowledge about the origin of the large living groups of marsupials and placentals has made considerable progress following recent important discoveries in two diferent disciplines of the life sciences, paleontology and molecular biology.