What caused the Sauk transgression?
The climate was subhumid, warm, and rainy. The sauk sequence was terminated abruptly about 490 million years ago when sea level suddenly dropped (on geological timescales, taking a few million years), leading to widespread erosion and the formation of a worldwide unconformity surface on top of the sauk sequence.
When was the Sauk transgression?
It dates from the late Proterozoic through the early Ordovician periods, though the marine transgression did not begin in earnest until the middle Cambrian. At its peak, most of North America was covered by the shallow Sauk Sea, save for parts of the Canadian Shield and the islands of the Transcontinental Arch.
What sequence of rocks indicates the occurrence of the Sauk transgression?
4. Extensive sequences of Cambrian marine sediments (sandstone, shale & fossil-bearing limestone) indicate that the continents were at times flooded by great shallow seaways. North America was almost completely drowned in Late Cambrian time by what came to be known as the Sauk transgression. 5.
What rock formation is the base of the Sauk transgression?
The Sauk transgression was one of the most dramatic global marine transgressions in Earth history. It is recorded by deposition of predominantly Cambrian non-marine to shallow marine sheet sandstones unconformably above basement rocks far into the interiors of many continents.
How long did the Sauk sequence last?
recognized of these are the Sauk Sequence (Late Precambrian to mid-Ordovician; about 650 to 460 million years ago), the Tippecanoe Sequence (mid-Ordovician to Early Devonian; about 460 to 400 million years ago), the Kaskaskia Sequence (Early Devonian to mid-Carboniferous; about 408 to 320 million years ago), and the …
What is the youngest cratonic sequence?
There have been six cratonic sequences since the beginning of the Cambrian Period. For North America, from oldest to youngest, they are the Sauk, Tippecanoe, Kaskaskia, Absaroka, Zuñi, and the Tejas.
What age is the Sauk sequence?
What causes cratonic sequence?
The most likely causes of these cycles is change in mid-ocean ridge volume, which is related to seafloor spreading rates. When Earth’s mid-ocean ridges spread rapidly, the ridges tend to be longer than usual; also, the greater heat elevates the lithosphere over the ridges.
What are Megasequences?
megasequence A stratigraphic sequence of rocks formed by sedimentation in a tectonically produced extensional basin, commonly at a constructive margin. A Dictionary of Earth Sciences.
Which of the following cratonic sequences is the oldest?
These sequences were given names. The oldest was the Sauk, followed by the Tippecanoe, Kaskaskia, Absaroka, Zuni, and Tejas.
Which Paleozoic cratonic is youngest?
Who is the father of stratigraphy?
geologist William Smith
The man credited as the “father of stratigraphy,” however, was the English engineer and geologist William Smith (1769-1839). In 1815 Smith produced the first modern geologic map, showing rock strata in England and Wales.