The High Stone EarthCache

This EarthCache is a joint effort between me and my son, aged 7, as part of his science project on stones.    He has been studying rocks this year, including their properties, rock types and the rock cycle. 

We both like the history of The High Stone, so we have tried to combine a spot of history with an EarthCache lesson aimed at a Year 3 student. 

About the High Stone

The High Stone is a grade II listed building (List entry Number: 1065570) at the junction of Hollybush Hill and New Wanstead.

The name of the area Leytonstone means the part of Leyton near the Stone.    However, due to boundary changes it now sits within Redbridge!

The Obelisk is made of Portland Stone and is in two parts:

1. The base:Legend has it that the base dates from Roman times, although others say it is a remnant of an 18^th Century stone.

2. The obelisk:This dates from only 1933 when the original stone was damaged by a vehicle and was replaced.

The High Stone was an important mile marker sitting at the junction between two of the main roads leading to East Anglia which are now Hollybush Hill and New Wanstead.  There are inscriptions on the four faces of the obelisk.  These are hard to read but when the stone setting was improved in 2013 a plaque was installed very close by and this details the four inscriptions.

The obelisk is also mentioned in reports of attacks by highwaymen in Epping Forest.  There is reference to one on the plaque from 1757 and a press account from the time (taken from 'Epping Forest: Then and Now') reads: "Whereas the post-boy bringing the Norwich mail from Epping Forest to this office was, this morning about four O'clock attacked and robbed on the road by the obelisk or High Stone, near Leytonstone in the county of Essex by a single highwayman on horseback who presented a pistol to the post-boy at the time, ordering him to deliver the mail otherwise he would blow his brains out, which obliged the post-boy to unstrap the mail and deliver it to the highwayman who took the whole Norwich mail before him upon his horse and rode away with it full speed towards Epping."

Lessons

1.  Stone Types

There are three main types of stone:

SEDIMENTARY

Sedimentary rocks are formed in three stages:

i) Sedimentation

Sediment is ‘matter’ that settles or is ‘deposited’ at the bottom of usually a liquid – like a lake or sea. This sediment can include minerals, small pieces of plants and other organic matter.

ii) Compaction

The weight of the sediments on top squashes the sediments at the bottom. This is called compaction. The water is squeezed out from between the pieces of rock and crystals of different salts form.

iii) Cementation

The crystals form a sort of ‘glue’ that sticks or cements the pieces of rock together. This process is called cementation.

These processes eventually make a type of rock called sedimentary rock. It may take millions of years for sedimentary rocks to form.

Limestone is an example of a sedimentary rock

IGNEOUS

Molten rock usually located deep within the mantle of the Earth that occasionally comes to the surface through cracks in the mantle or through the eruption of volcanoes is called Magma. Igneous rock is formed when magma cools and solidifies, it may do this above or below the Earth's surface. Igneous comes from the Latin word ignis meaning fire.

The upper section of the Earth's crust is made up of around 95% igneous rock.

Igneous rocks contain randomly arranged interlocking crystals. The size of the crystals depends on how quickly the molten magma solidified. The more slowly the magma cools, the bigger the crystals.

There are many different types of igneous rocks with granite and basalt being examples.

METAMORPHIC

Metamorphic rocks are formed from other types of rock through extreme heat and or pressure. The minerals they contain are changed chemically or physically.

The change can happen through heat from the Earth’s interior, through the pressure of the movement of the tectonic plates, or just the sheer weight of the material above it.

Limestone metamorphoses into marble. Similarly granulite is a metamorphic rock from basalt.

2.   Portland Stone

Portland stone is a type of Limestone (ie a Sedimentary rock).  Limestones are mostly made of calcium carbonate. This comes originally from the bodies of many small organisms which build their framework out of calcium carbonate crystals. When these organisms die they accumulate and become fossilised over millions of years.

Portland Stone originates from the Isle of Portland in Devon. It is one of the most popular building stones in Britain.   Many of the famous buildings in London are covered in Portland stone, including St Pauls, the BBC building at the top of Regent Street and even Green Park tube station.

As it erodes, Portland stone commonly exposes different types of fossils.   

Questions

1. Describe the stone in the two parts of the landmark. Compare and contrast them.

2. Legend has it that the base stone is from Roman times, but others think it is from the c.18^th Century. Based on your observations above, when do you think it is from?

3. Portland stone commonly has fossils in it. There are only a few to be found on the obelisk. Can you describe them and, through a spot of research, name them?

4. To prove you went to the site….We think the plaque writers made a mistake on the West Face inscription. Can you tell us what word they got wrong on the plaque and what the actual word is on the obelisk?

5. Optional task...Take a photo of yourself at The High Stone!

Message me (using email or the Message Center) your answers to the tasks. DO NOT post answers in your log. After completing ALL the requirements, log your find.   I will respond with any queries.