Cobequid Iron EarthCache

Cobequid Iron

Geologically, the Cobequid Mountains are considered part of the Appalachians. The Cobequid Mountains trace their geologic history to the Precambrian and Devonian ages; consequently the mountains are composed of a combination of sediments, granites, and volcanic rock all of which has been crushed and folded by continental drift when this part of Nova Scotia was located at the centre of the Pangea supercontinent. Subsequent erosion over millions of years has resulted in the present-day low range of mountains and rolling hills.

Geology

The iron deposits lie in a group of pre-Carboniferous rocks that underlie the south flank of the Cobequid Mountains. The rock types found in the group are sedimentary rocks or volcanic ash beds, quartzite or silicified tuff, chlorite and graphitic schists, and conglomerates. They are highly deformed by folding and faulting, and intruded by acid plutonic rocks and by minor basic intrusions. A zone with westerly striking, steeply dipping lenses of 'ankerite' and ferruginous carbonate lies about half a mile north of a major fault and continues parallel with it for 20 kilometers.

The most important iron-bearing minerals are 'ankerite' (really iron rich dolomite) and siderite, thought to have been derived from a plutonic magma and deposited by solutions at a sufficient distance from the heated mass to allow them to cool and to be deposited in their present form as carbonates. They underwent subsequent dislocations during the Carboniferous. Denudation gradually exposed the shattered veins and the carbonates of iron were oxidized to ochre limonite. Carbonated waters dissolved and transported some of the iron, redepositing it in the form of goethite, botryoidal limonite, and hematite. The workable ore consisted of these secondary hydrated oxides of iron.

In geology, denudation involves the processes that cause the wearing away of the Earth's surface by moving water, by ice, by wind and by waves, leading to a reduction in elevation and in relief of landforms and of landscapes.

The Londonderry iron district of the Cobequid mountains in Nova Scotia was mined for nearly 60 years, proving to be one of the most important mining districts of the province. In recent years, good specimens of goethite have collected from the area. For more information visit the Londonderry Iron Works Memorial Park (GC91M0V).

To log this Earthcache visit the viewing location. Please answer the following questions and send in a timely manner to my geocaching profile or email. Answers not received will result in deleted logs.

This is best seen going North on the 104, the shoulder is wide for parking.

This is a long impressive outcrop so take some time to explore it.

In 2022, two thirds of the outcrop was used for construction.

Questions:

1. How long and high is the outcrop?

2. Do you see erosion and why?

3. What colours do you see on the outcrop?

4. Post a picture in your log with a personal item or hand in picture to prove you were there.

[REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please provide a photo of yourself or a personal item in the picture to prove you visited the site.