Marl in the context of "Eagle Ford Group"

Chert (/tʃɜːrt/) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO₂). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood. Where chert occurs in chalk or marl, it is usually called flint.

Chert is typically composed of the petrified remains of siliceous ooze, the biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of diatoms, silicoflagellates, and radiolarians. Precambrian cherts are notable for the presence of fossil cyanobacteria. In addition to microfossils, chert occasionally contains macrofossils. However, some chert is devoid of any fossils.

Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. The primary objective of biostratigraphy is correlation, demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to help identify biozones, as they make up the basic biostratigraphy units, and define geological time periods based upon the fossil species found within each section.

Basic concepts of biostratigraphic principles were introduced in the early 1800s. A Danish scientist and bishop by the name of Nicolas Steno was one of the first geologists to recognize that rock layers correlate to the Law of Superposition. With advancements in science and technology, by the 18th century it began to be accepted that fossils were remains left by species that had become extinct, but were then preserved within the rock record. The method was well-established before Charles Darwin explained the mechanism behind it—evolution. Scientists William Smith, George Cuvier, and Alexandre Brongniart came to the conclusion that fossils then indicated a series of chronological events, establishing layers of rock strata as some type of unit, later termed biozone. From here on, scientists began relating the changes in strata and biozones to different geological eras, establishing boundaries and time periods within major faunal changes. By the late 18th century the Cambrian and Carboniferous periods were internationally recognized due to these findings. During the early 20th century, advancements in technology gave scientists the ability to study radioactive decay. Using this methodology, scientists were able to establish geological time, the boundaries of the different eras (Paleozoic, Mesozoic, Cenozoic), as well as Periods (Cambrian, Ordovician, Silurian) through the isotopes found within fossils via radioactive decay. Current 21st century uses of biostratigraphy involve interpretations of age for rock layers, which are primarily used by oil and gas industries for drilling workflows and resource allocations.

Terramare, terramara, or terremare is a technology complex mainly of the central Po valley, in Emilia, Northern Italy, dating to the Middle and Late Bronze Age c. 1700–1150 BC. It takes its name from the "black earth" residue of settlement mounds. Terramare is from terra marna, "marl-earth", where marl is a lacustrine deposit. It may be any color but in agricultural lands it is most typically black, giving rise to the "black earth" identification of it. The population of the terramare sites is called the terramaricoli. The sites were excavated exhaustively in 1860–1910.

These sites prior to the second half of the 19th century were commonly believed to have been used for Gallic and Roman sepulchral rites. They were called terramare and marnier by the farmers of the region, who mined the soil for fertilizer. Scientific study began with Bartolomeo Gastaldi in 1860. He was investigating peat bogs and old lake sites in north Italy but did some investigations of the marnier, recognizing them finally as habitation, not funerary, sites similar to the pile dwellings further north.

Qumran (/ˈkʊmrɑːn/; Hebrew: קומראן; Arabic: خربة قمران Khirbet Qumran) is an archaeological site in the West Bank managed by Israel's Qumran National Park. It is located on a dry marl plateau about 1.5 km (1 mi) from the northwestern shore of the Dead Sea, about 10 km (6 mi) south of the historic city of Jericho, and adjacent to the modern Israeli settlement and kibbutz of Kalya.

The Hellenistic period settlement was constructed during the reign of Hasmonean leader John Hyrcanus (134–104 BCE) or somewhat later. Qumran was inhabited by a Jewish sect of the late Second Temple period, which most scholars identify with the Essenes; however, other Jewish groups were also suggested. It was occupied most of the time until 68 CE and was destroyed by the Romans during the First Jewish–Roman War, possibly as late as 73 CE. It was later used by Jewish rebels during the Bar Kokhba revolt. Today, the Qumran site is best known as the settlement nearest to the Qumran Caves where the Dead Sea Scrolls were hidden, caves in the sheer desert cliffs and beneath, in the marl terrace. The principal excavations at Qumran were conducted by Roland de Vaux in the 1950s, and several later digs have been carried out.

Opal is a hydrated amorphous form of silica (SiO₂·nH₂O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt.

The name opal is believed to be derived from the Sanskrit word upala (उपल), which means 'jewel', and later the Greek derivative opállios (ὀπάλλιος).

Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires.

Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey or black, green, white, or brown in colour, and has a glassy or waxy appearance. A thin, oxidised layer on the outside of the nodules is usually different in colour, typically white and rough in texture. The nodules can often be found along streams and beaches.

The mineral pyrite (/ˈpaɪraɪt/ PY-ryte), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS₂ (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.

Pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to the nicknames brass, brazzle, and brazil, primarily used to refer to pyrite found in coal.

Liming is the application of calcium- (Ca) and magnesium (Mg)-rich materials in various forms, including marl, chalk, limestone, burnt lime or hydrated lime to soil. In acid soils, these materials react as a base and neutralize soil acidity. This often improves plant growth and increases the activity of soil bacteria, but oversupply may result in harm to plant life. Modern liming was preceded by marling, a process of spreading raw chalk and lime debris across soil, in an attempt to modify pH or aggregate size. Evidence of these practices dates to the 1200's and the earliest examples are taken from the modern British Isles.