1GL Bolt: Thirkleby Bridge   

Bolt on East face of South pier of Thirkleby Bridge ; 3.12 ft. above lower surface of keystone [1GL, Selby to Newcastle-upon-Tyne, Mark No. 73] - approximate location.

Location
Grid reference: SE 4727 7753.
Landranger 100: Malton & Pickering, Helmsley & Easingwold.
Structure: Bridge.
Waypoint: BT0777.

Neighbouring Bench Marks

BM	Stockhill Green 1.44km to the northwest.
BOLT	Birdforth Bridge 2.28km to the southeast.
BOLT	Bagby, Church 3.23km to the north.
BM	Thormanby, Black Bull Hotel 3.37km to the southeast.
BOLT	Sowerby, St. Oswald's Church 5.66km to the northwest.

The nearest fundamental bench mark is Northallerton, 16.71km to the north.

First Primary Levelling, England & Wales (1840-60)
This bench mark was used during the First primary levelling, England & Wales, and was levelled with a height of 110.2940 feet [33.6176 metres] above mean sea level (Liverpool datum). It was included on the Selby to Newcastle-upon-Tyne levelling line. The surveyor's description was Bolt on East face of South pier of Thirkleby Bridge ; 3.12 ft. above lower surface of keystone.