Abstract The Southern Coastal region includes a narrow coastal strip of sedimentary deposits extending from the vicinity of San Onofre on the north to the Mexican border on the south. This strip of sedimentary rocks of Cretaceous, Tertiary, and Quaternary age varies in width from 4 to 20 miles. Exposures of pre-Upper Cretaceous crystalline rocks are adjacent on the east in the Peninsular Ranges and extend westward, forming the basement below the marginal sedimentary belt. The area of sedimentary rocks is about 949 square miles. The northern part of the region, in the vicinity of San Onofre, is a southeastward extension of the Los Angeles Basin; it is the only part of the province in which marine Miocene sedimentary rocks are known. The southern part of the region consists of the San Diego Pliocene-Pleistocene basin. These two basin areas are underlain by Eocene and Cretaceous sediments, and the strip between them is occupied by an Eocene sedimentary series overlying Cretaceous sediments at shallow depths. In the vicinity of San Onofre, the Upper Cretaceous Chico formation lies directly on the pre-Upper Cretaceous granitic rocks with their inclusions of Triassic and older slates and schists. The Chico formation is very largely conglomerate and breccia. A boulder conglomerate near the base of the Chico may be part of the Trabuco formation of the Santa Ana Mountains. The overlying Eocene consists of massive conglomerate, yellow and brown sandstones, and shale of upper Eocene age, probably, in part at least, the equivalent of the Poway conglomerate

This report discusses the geography, systematic geology, structure, and economic deposits in the Coast Ranges of Central California involving nine quadrangles with an area of approximately 2215 square miles of which about a fifth is water. The hills of the Coast Ranges immediately north of San Francisco occupy three north-westward-trending areas which are separated by the San Andreas fault and northern extension of the Haywards fault system. Each area is composed of distinct groups of rock formations. The oldest formations investigated, perhaps of Paleozoic age, consist of metamorphosed sediments, volcanic rocks, and quartz diorite and are exposed in Point Reyes Peninsula. They form a small residual mass of what was probably an extensive coastal land that lay west of the present coast of California but which late in the Tertiary or early in the Pleistocene foundered beneath the Pacific Ocean. This former land area is believed to have furnished many of the sediments laid down during Mesozoic and Tertiary time that are now exposed in the mountains between the San Andreas fault and the Sacramento Valley. The next younger rocks are a thick series of sandstones and associated basic igneous rocks which are widely distributed throughout the Coast Ranges of California and southern Oregon and are known as the Franciscan group. They constitute the surface rock exposures in most of the area between the San Andreas fault and the northern extension of the Haywards fault zone. The Franciscan has a thickness of 7000 feet or more. It contains no fossils except poorly preserved radiolarians in the cherts and Foraminifera in the limestones, which do not permit of an exact age determination. Recently discovered ichthyosaur head bones and teeth from cherts thought to belong to the Franciscan group are closely allied to a species from the lower Portlandian of Europe. From evidence obtained within the mapped area the Franciscan is younger than the time of intrusion of the quartz diorite into the Sur series which may have been during the late Paleozoic. Its upper age limit is uncertain because of fault contacts with the Knoxville formation. It has been considered by other writers from evidence obtained outside of the mapped area as in part contemporaneous with the Knoxville. The area between the Petaluma-Cotati Valley trough and the Sacramento Valley is composed of more than 30,000 feet of Jurassic to Quaternary marine and fresh-water sediments, together with about 1200 feet of Pliocene andesites, rhyolites, and tuffs. These sediments probably accumulated in structural troughs whose areas and physical environments changed greatly during the Cretaceous and Tertiary. The lower portion consists of clay shales and subordinate amounts of sandstone and conglomerate as much as 17,000 feet thick, containing a marine fauna of ammonites, pelecypods, and gastropods. These rocks include the Jurassic and Lower Cretaceous portions of the Knoxville formation and the Upper Cretaceous Chico. Several faunal zones may be distinguished in the Knoxville, but the formation in the mapped area cannot be subdivided on a lithologic basis. The Chico formation consists of interbedded shales and sandstones about 7000 feet thick. The Paleocene is represented by the Martinez formation, and the Eocene in ascending order by the Capay shale and the Domengine and Markley sandstones. The formations of the Paleocene and Eocene series consist of marine sediments ranging in thickness from 2000 to 5000 feet that were deposited in embayments far more restricted in area than the seas of the Upper Jurassic and Cretaceous time. The marine sedimentary formations of the Oligocene and lower part of the Miocene series occupy still more restricted areas than those of the Paleocene and Eocene, and near Carquinez Strait are more than 5000 feet thick. The upper Miocene sand-stones of the San Pablo group are far more widely distributed and are nearly 2500 feet thick. They are characteristically coarse-grained and were deposited in moderately shallow water which locally was brackish or fresh. The Pliocene rocks crop out extensively in the north-central part of the area and consist largely of alternating flows of andesite, basalt, dacite, and rhyolite together with associated tuffs and agglomerates, whose total thickness is 100 to 1200 feet. In Santa Rosa and Petaluma quadrangles marine sandstones contain invertebrate fossils closely allied to those of the Merced formation in San Francisco. The beds in Marin and Sonoma counties are about 250 feet thick and rest unconformably upon the Franciscan group. Near Petaluma Valley they interfinger with tuffs. Before the Pliocene volcanics accumulated the entire area east of the San Andreas fault was folded and faulted, after which it was deeply eroded. The Pliocene volcanics were laid down on the beveled surface of the older rocks and later were moderately folded and broken by normal faults and locally overturned and broken by thrust faults. During the Quaternary period the Coast Ranges in Middle California, in common with areas to the north and south, were undergoing crustal deformation by differential elevation and depression of the numerous fault blocks, some of which at times were temporarily beneath sea level. Stream erosion adjusted to the differentially elevated blocks and left a somewhat obscure record of the complex Quaternary history. Igneous activity was confined mainly to three widely separated epochs. The pre-Knoxville was characterized by intrusions of quartz diorite. The peridotites, gabbros, and basalts associated with the Franciscan group formed during the second epoch of activity in the early part of the late Jurassic. The third was characterized by extrusion of andesitic and rhyolitic materials during the middle and late Pliocene. Volcanoes may have been active during the intervening periods in areas not far from that studied, as tuflaceous products are present in the Oligocene and Miocene sediments. Important associated mineral resources include mercury, magnesite, limestone, road metal, building stone, clays, and surface and ground water.

North American Paleocene land mammal ages are the Mantuan, Puercan, Torrejonian, Tiffanian, and Clarkforkian. These ages (and associate stages) are subdivided into 16 zones or subzones, varying in duration from 0.1 to 2.9 m.y., defined by widespread species. Although gross evolutionary changes during the first four of these ages are about equal, their durations are very unequal. As defined by magnetostratigraphy and fossil occurrence, the Mantuan is about 0.2 m.y., the Puercan about 1.1 m.y., the Torrejonian about 3.1 m.y., the Tiffanian about 6.1 m.y., and the Paleocene part of the Clarkforkian about 1.3 m.y. in duration. Puercan encompasses normal magnetozone 29, Torrejonian zones 28 and 27, and the Tiffanian–Clarkforkian boundary falls in zone 25. The type Rio Chico Formation of Patagonia is of mid-Tiffanian to Clarkforkian age. Problems in the identification of magnetozones in the San Juan Basin have arisen because an unconformity is present between the Kirtland Shale and the Ojo Alamo Sandstone, and for some years an extra normal chron was falsely identified. When this hiatus is taken into account, marine and terrestrial fossil correlations agree with magnetozone correlations throughout Upper Cretaceous and Paleocene rocks. The Danian stage in marine rocks in North Dakota is equivalent to Mantuan through early Tiffanian; the Thanetian is exactly equivalent to mid-Tiffanian to early Clarkforkian. The rate of Paleocene sedimentation in the major basins of North America does not depart from linearity much more than the contemporary rate of seafloor spreading. Terrestrial rates of sedimentation vary from a peak of 568 bubnoffs (b) (meters per million years) for the Hoback Formation at the Rocky Mountain front to 99 b in the San Juan Basin and 15 b in the Black Peaks Formation in Texas, compared to 2.7 b at Gubbio, Italy. Sedimentation rates along a transect through the Bighorn, Powder River, and Williston basins follow the equation Y = 200X −0.25 , where Y is the sedimentation rate in bubnoffs and X is the radial distance in kilometers from the Absaroka thrust. Absolute taxonomic and morphologic rates of evolution of the most rapidly evolving mammals during the Bugcreekian–Mantuan interval across the Cretaceous–Paleocene boundary peak at 5 genera per m.y. and 3.85 darwins (a rate of measurement defined in the text), the fastest rates known in the fossil record, and decline exponentially to more normal rates of 1 species per m.y. and 0.5 darwins by the Tiffanian. Range charts of 299 species of ungulates, primates, and multituberculates permit ready identification of zones. Seven new species of multituberculates are described, and shape and metrical properties of latest Cretaceous–Paleocene neoplagiaulacid multituberculates are summarized for ease in identification.

Abstract Hot springs along Sulphur Creek in Colusa County, California, have been recognized for about 130 years. Several researchers have proposed that the hot spring fluid there is derived from mixing of “connate” or “evolved connate” water which is derived from ancient seawater deposited in the Mesozoic sedimentary rocks. This water, which is similar in composition to Complexion Spring, mixes with meteoric water to form Wilbur Springs and other hot spring waters along Sulphur Creek. A δD - δ 18 O plot shows that Complexion Spring really does not plot along this trend; it must be isotopically modified to plot along the trend. Tuscan Springs, which is located 140 km NNE of Wilbur Springs, just NE of Red Bluff, has chemical and isotopic characteristics which are similar to the Sulphur Creek hot springs. Tuscan Springs vent from the Chico Formation of the Great Valley sequence and indicate that Tuscan Springs and Wilbur Springs are both derived from waters originating in the Great Valley sequence. Also δ 11 B correlates well with Cl, δD and δ 18 O, which originate in the Great Valley sequence, suggesting a similar source for the higher d 11 B values. Chemical geothermometry of the Sulphur Creek hot springs indicates a reservoir temperature of ~ 180 °C. This temperature agrees with measured homogenization temperatures from fluid inclusion which range from 150 to 180 °C. The calculated cation geothermometer temperatures are affected by the presence of dissolved Mg, even though the concentrations appear low.