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Grand River Geology: Conglomerate EarthCache

This cache has been archived.

Camroo: This area has changed so vastly since publication, making it much harder to receive the answers, so I'll be taking this one off the map. Thanks for the visits everyone.

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Hidden : 9/17/2018
Difficulty:
2.5 out of 5
Terrain:
2.5 out of 5

Size: Size:   other (other)

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Geocache Description:


I Was out looking at the mill and noticed a rock that seemed unnatural. i did a little searching and figured out what i was looking at was conglomerate!

So What is Conglomerate?

Conglomerate is a Sedimatary Rock Composed Of Many Little Gravel Sized Rocks.

These Rocks Are Called Clasts.

Some Conglomerates Contain Finer Grained Sediments, These Include.

Sand Silt Or Clay. 

Some Of The Larger Ones Would Be: 

Calcium Carbonate, iron oxide, silica or hardend clay.

Conglomerates Are Usually Found In the Following Sedimentary Enviroments:

Deepwater marine

In turbidites, the basal part of a bed is typically coarse-grained and sometimes conglomeratic. In this setting, conglomerates are normally very well sorted, well-rounded and often with a strong A-axis type imbrication of the clasts.[8]

Shallow marine

Conglomerates are normally present at the base of sequences laid down during marine trangressions above an unconformity, and are known as basal conglomerates. They represent the position of the shoreline at a particular time and are diachronous.[9]

Fluvial

Conglomerates deposited in fluvial environments are typically well rounded and well sorted. Clasts of this size are carried as bedload and only at times of high flow-rate. The maximum clast size decreases as the clasts are transported further due to attrition, so conglomerates are more characteristic of immature river systems. In the sediments deposited by mature rivers, conglomerates are generally confined to the basal part of a channel fill where they are known as pebble lags.[10] Conglomerates deposited in a fluvial environment often have an AB-plane type imbrication.

Alluvial

Alluvial deposits form in areas of high relief and are typically coarse-grained. At mountain fronts individual alluvial fans merge to form braidplains and these two environments are associated with the thickest deposits of conglomerates. The bulk of conglomerates deposited in this setting are clast-supported with a strong AB-plane imbrication. Matrix-supported conglomerates, as a result of debris-flow deposition, are quite commonly associated with many alluvial fans. When such conglomerates accumulate within an alluvial fan, in rapidly eroding (e.g., desert) environments, the resulting rock unit is often called a fanglomerate.[8]

Glacial

Glaciers carry a lot of coarse-grained material and many glacial deposits are conglomeratic. Tillites, the sediments deposited directly by a glacier, are typically poorly sorted, matrix-supported conglomerates. The matrix is generally fine-grained, consisting of finely milled rock fragments. Waterlaid deposits associated with glaciers are often conglomeratic, forming structures such as eskers.[10]

Logging Tasks:

1. At The Posted Coords You Will Find Some Conglomerate. Explain The Texture Of This Type.

2. How Large This Conglomerate. Compare It To The Size Of Your Hand. 

Optional: Take A Photo Of You At GZ With The Grand River In The Background

Additional Hints (No hints available.)