The Alston Block is a term used by geologists to describe the geological structure of the North Pennines

North Pennines

The North Pennines is the northernmost section of the Pennine range of hills which runs north-south through northern England. It lies between Carlisle to the west and Darlington to the east...

 of northern England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 and which forms a part of the Pennine Block & Basin Province which originated during the Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 period. It is defined by the Stublick and Ninety Fathom Faults to the north, the Pennine Fault to the west and the Stainmore

Stainmore

Stainmore is a civil parish in the Eden District of Cumbria, England, including the villages of North Stainmore and South Stainmore. It has a population of 253.- Geography :...

 Trough to the south. It is in essence a horst underlain by the Weardale

Weardale

Weardale is a dale, or valley, of the east side of the Pennines in County Durham, in England. Large parts of Weardale fall within the North Pennines Area of Outstanding Natural Beauty - the second largest AONB in England and Wales. The upper valley is surrounded by high fells and heather grouse...

 Granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 which provides sufficient buoyancy to maintain this piece of the upper crust

Crust (geology)

In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...

 as an area of raised relief. To its west lies the Vale of Eden

Vale of Eden

The Vale of Eden is formed by the course of the River Eden, one of the major rivers of Northwest England. It is however of much greater extent than the actual valley of the river, lying between the Cumbrian Mountains , and the northern part of the Pennine Range. It lies entirely within the county...

and to its north is the Northumberland Trough.
The area is also known for its mineral wealth.