Trinity Sea Stacks EarthCache
Hidden : 8/11/2017
Difficulty:
2 out of 5
Terrain:
5 out of 5

Size: Size: other (other)

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Geocache Description:

TO LOG THIS CACHE:
 1) Describe in your own words what state the stacks are at the provided coordinates
2) Estimate the width of the stacks and provide details with your answer
3) Based on the chart and rock details listed below, which rock is most prominent, and what types of rock do you think are eroding the fastest.
4) [Not Mandatory] Post a picture of yourself at the cache site.

Note: DO NOT ATTEMPT TO ACCESS THIS CACHE FROM THE LAND ON THE TOP. NOT ONLY WILL YOU NOT BE ABLE TO GET THE REQUIRED INFORMATION, IT IS INCREDIBLY DANGEROUS.

Sea stacks are a striking example of the erosive power of the sea over long periods. Sea Stacks form when sea caves on opposites of a headland merge to form an arch. The arch later falls in, leaving the seaward part of the headland as an isolated rock pillar. The sea stacks you will see at the posted coordinates are a result of the vertical nature of the rock layers, whereby hard, resistant beds are inter-layered with softer less resistant beds. The sea more easily erodes the softer beds between the more resistant beds to form recessive areas and eventually sea stacks that eventually merge.


The primary makeup of Trinity is:

Shale:Shale is a fine-grained, classic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. Mudstones, on the other hand, are similar in composition but do not show the fissility.


Siltstone:Siltstone is a clastic sedimentary rock. As its name implies, it is primarily composed (greater than 2/3) of silt sized particles, defined as grains 2–62 µm or 4 to 8 on the Krumbein phi scale. Siltstones differ significantly from sandstones due to their smaller pores and higher propensity for containing a significant clay fraction. Although often mistaken as a shale, siltstone lacks the fissility and laminations, which are typical of shale. Siltstones may contain concretions. Unless the siltstone is fairly shaly, stratification is likely to be obscure and it tends to weather at oblique angles unrelated to bedding. Mudstone or shale are rocks that contain mud, which is material that has a range of silt and clay. Siltstone is differentiated by having a majority silt, not clay.


Sandstone: Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions.


Conglomerate: Conglomerate is a coarse-grained clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts, e.g., granules, pebbles, cobbles, and boulders, larger than 2 mm (0.079 in) in diameter. Conglomerates form by the consolidation and lithification of gravel. Conglomerates typically contain finer grained sediment, e.g., either sand, silt, clay or combination of them, called matrix by geologists, filling their interstices and are often cemented by calcium carbonate, iron oxide, silica, or hardened clay.


Glaciogenic Diamictite: is a type of lithified sedimentary rock that consists of nonsorted to poorly sorted terrigenous sediment containing particles that range in size from clay to boulders, suspended in a matrix of mudstone or sandstone. The term was coined by Flint and others as a purely descriptive term, devoid of any reference to a particular origin. Some geologists restrict the usage to nonsorted or poorly sorted conglomerate or breccia that consists of sparse, terrigenous gravel suspended in either a mud or sand matrix


Volcanic Rocks: Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from magma erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface.

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