Howth Landscape

James McMahon 21508156

Plate Reconstruction (Sarah Gatley, 2004).

History

Howth first came about when it was first plundered by the Vikings around 819 (S., 2021). The Eastern Shores of Ireland were colonised by Norse Vikings during the Anglo-Irish invasion (S., 2021). Howth Head is a rocky peninsula which is situated on the Northern side of the Dublin Bay (NPWS, 2016). The Peninsula is composed of Cambrian slates and quartzites which is joined by a post-glacial raised beach (NPWS, 2016). The Cambrian period which occurred 545-495 million years ago happened when the Iapetus Ocean continued to open between Laurentia and Gondwana (Sarah Gatley, 2004). By the end of the period it had reach it’s maximum width up to 5000 km which is similar in scale to today’s Atlantic (Sarah Gatley, 2004). The climate of Howth and Howth Head is dry and warm and is home to an array of diverse flora and fauna (NPWS, 2016).

Howth

(33) Howth - Ireland - Discover the surroundings of Dublin - YouTube

Bedrock

(GSI, 2022).

Bedrock is the solid rock at or below the land surface (GSI, 2022). Over much of Ireland, the bedrock is covered by such materials as soli and gravel (GSI, 2022). The GSI map shows the land surface of Ireland and in this case Howth. The bedrock at Howth is from the Cambrian period and is this particular area it consists of quartzite and mudstone (GSI, 2022).

(GSI, 2022).

It consists of a melange of quartzite blocks and pebbles in a mudstone to siltstone matrix (GSI, 2022). This melange is possibly a result of slumping of an interbedded quartzite-mudstone sequence (GSI, 2022).

Types of Rocks

Quartzite found in Howth

The main rock type formed in the Cambrian and within Howth are greywackes, slates and quartzite (Sarah Gatley, 2004). Greywacke is a rock composed of muddy sands and sedimentary structures within the rock which indicates that they were deposited mainly by turbidity currents (Sarah Gatley, 2004). The quartzite sand was produced by winnowing of mud from sand in an active sediment deposit area such as a beach (Sarah Gatley, 2004). The quartzite units’ range in thickness from 10 metres to over 100 metres (Sarah Gatley, 2004).

Greywacke found in Howth

These quartzites are resistant to erosion and form the high ground within the area (Sarah Gatley, 2004). When the layer of sediment is built up movement on faults caused the sediments to slump and mix in places (Sarah Gatley, 2004). These slump places alternate with undeformed sediments which is well developed at Howth (Sarah Gatley, 2004).

Where these rocks are used

Howth Stone Quarry

Howth is home to a stone quarry and has been mined for about five generations (Peninsula Stone Landscapes, 2022). The stone which is extracted is completely unique to Howth and is seen on many pillars throughout Howth (Peninsula Stone Landscapes, 2022). Quartzite the rock found in Howth is also quarried and used throughout Howth (Peninsula Stone Landscapes, 2022). The quartz is used to create walls of all shapes and sizes and can also be used on walls and fireplaces due to its beautiful look and colourful nature (Peninsula Stone Landscapes, 2022).

Quaternary Deposits

Till From Quartzite

The Quaternary period is the most recent major subdivision period of the geological record and extends to the present day (Lowe, 1997). Quaternary sediments also come out of this process and the main types of are tills, alluvium, lacustrine sediments, peat, and glacial/fluvial deposits (GSI, 2022).

Quaternary deposit map GSI

The quaternary deposit which is found on the GSI map in Howth was till derived from quartzites. Till is deposited directly by glacial ice showing no stratification (Britannica, 2011). Till sometimes called boulder clay being composed of clay they are deposited from ice and have undergone little water transport (Britannica, 2011).