Search results
Results from the WOW.Com Content Network
The Mercia Mudstone Group is now divided into five formations recognised and mappable across its entire outcrop and subcrop. The formations are a mix of mudstones, siltstones, sandstones and halites. Historically this sequence of rocks has been subdivided in different ways with different names in each of the basinal areas in which it is found.
A pile up to several hundred metres thick of Triassic sandstones, mudstones and siltstones underlies Wirral, Liverpool and the coastal plains to the north. The following sequence is encountered within Merseyside: Mercia Mudstone Group. Sidmouth Mudstone Formation (formerly 'Keuper Marl') Tarporley Siltstone Formation (formerly 'Keuper Waterstones')
The simplest definition is that a mudstone is a fine-grained clastic sedimentary rock that is not laminated or fissile. [5] Most definitions also include a requirement that the rock contain significant amounts of both silt- and clay-sized grains.
More recently, however, [4] there has been the recognition that it is the Mercia Mudstone Group which is seen to thicken markedly into faults imaged on seismic data rather than the Sherwood Sandstone Group. This work demonstrates the Mercia Mudstone Group to be a syn-rift phase of deposition, with the fine grained nature of the sedimentary ...
It was in this type of environment that the Mercia Mudstone Group (formerly Keuper Marl) was deposited. The sequence of formations in the Sherwood and Mercia mudstone groups in this region illustrates clearly the upward transition from continental fluvial to deltaic and littoral marine and ultimately to the hypersaline lake epeiric sea ...
The name 'Mercia' is a Latinisation of an Old English word derived from the Mercian Old English, Merce, meaning "borderland". [29] The dialect thrived between the 8th and 13th centuries and was referred to by John Trevisa , writing in 1387: [ 30 ]
Mudstones, shales, lutites, and argillites are common qualifiers, or umbrella terms; however, the term mudrock has increasingly become the terminology of choice by sedimentary geologists and authors. The term "mudrock" allows for further subdivisions of siltstone, claystone, mudstone, argilite and shale. For example, a siltstone would be made ...
A further presumed unconformity separates the breccia from the mudstones of the overlying Mercia Mudstone Group which underlie the larger part of the low ground between Exmoor and North Hill. At the top of the group is a 25m thickness of mudstones with gypsum referred to as the Blue Anchor Formation. Above this are around 12m thickness of ...