Varves Lamination Sedimentary Rock

Laminae are normally smaller and less pronounced than bedding.

Varves lamination sedimentary rock.

A single sedimentary rock can have both laminae and beds. A varve is an annual layer of sediment or sedimentary rock. When sedimentary rocks have no lamination at all their structural character is called massive bedding. The term first appeared as hvarfig lera on the first map produced by the geological survey of sweden in 1862.

In geology lamination is a small scale sequence of fine layers that occurs in sedimentary rocks. Of the many rhythmites found in the geological record varves are one of. These types of lamination are attributed to successive deposits of layers. A varve is an annual layer of sediment or sedimentary rock.

Thus lamination consists of thin units in bedded or layered sequence in a natural rock succession whereas stratification consists of bedded layers or strata in a geologic sequence of interleaved sedimentary rocks. Laminae that represent seasonal changes similar to tree rings are called varves. Initially varve referred to each of the separate components comprising a single annual layer in glacial lake sediments but at the 1910 geological congress the swedish geologist gerard de geer. The value of varves as climatic and paleoclimatic proxies lies in 1 demonstration that they are annual deposits and therefore may be used to determine absolute chronology and 2 assessment that their sedimentary properties relate demonstrably to hydroclimatic processes.

The word varve derives from the swedish word varv whose meanings and connotations include revolution in layers and circle. Terms such as annually laminated are synonymous with varve. Sedimentology experiments on lamination of sediments resulting from a periodic graded bedding subsequent to deposition a contribution to the explanation of lamination of various sediments and sedimentary rocks. However structures from several millimetres to many centimetres have been described as laminae.

Any sedimentary rock composed of millimeter or finer scale layers can be named with the general term laminite. Varved deposit any form of repetitive sedimentary rock stratification either bed or lamination that was deposited within a one year time period. A varve is any sedimentary bed or lamination deposit within the period of one year or any pair of contrasting laminae representing seasonal sedimentation as summer and winter within the period of one year. These sedimentation experiments have been conducted in still water with a continuous supply of heterogranular material.

More beds and the term lamina is sometimes applied to a unit less than one centimetre in thickness. In its broadest sense the term is applied to the layer of sediment deposited in a single year. Laminae laminites varves etc.