A geotrail guide giving more information about the
Cleveland Dyke at Cliff Rigg Quarry, Great Ayton,
North Yorkshire can be downloaded on the following website:
need adobe acrobat reader which you can download HERE).
This period began with another major lowering of
sea-level together with uplift, and nearly all of Britain, apart from the
south-east emerged as land. Because of this, it is most likely that no
Tertiary sediments were deposited in Northern England, although thick
sequences are known offshore beneath the North sea.
western side of the British Isles was affected by the opening of the North
Atlantic since, by the early Tertiary, the
spreading North Atlantic ridge had developed far enough north to begin
splitting Northern Europe from Greenland. Separation
of Greenland from Western Scotland and Ireland was
preceded by igneous activity, viz. volcanic eruptions and the intrusion of
dykes, e.g. in Skye, Mull, Staffa (Fingal's Cave) and Northern Ireland (the
Uplift and the development of the constructive plate
margin on the western side of the British Isles were responsible for the
general tilting of Britain towards the south-east as well as the renewed
activation of major faults, e.g. those surrounding the Alston Block.
rising western and northern areas of Britain consequently underwent a great
deal of erosion thus exposing much older rocks below, while progressively
younger rocks crop out as one travels south-east. It is believed that it was
Tertiary earth movements which raised the Lake District area into a dome from
which thousands of metres of rocks were eroded away to reveal the underlying
It was during this period of separation resulting in
crustal tension that a number of linear igneous rocks known as dykes, e.g.
the Cleveland, Tynemouth and Acklington Dykes composed of a type of basalt, were intruded.
These are the only tertiary rocks to be seen in Northern England. The
Cleveland Dyke and the sites where it was quarried for roadstone
can be seen in several places, e.g. at Great Ayton, and at Castleton. In
fact, from the the vantage point of Roseberry
Topping the dyke, being a more resistant rock, can be seen to form a distinct
ridge running in a WNW-ESE direction.
trend in global cooling began during the Tertiary, and this was to culminate
in the sequence of cold and temperate climates which have affected Britain in
the last 2 million years.