Geological Brimham
The rocks at Brimham have been made by entirely natural processes that have taken many millions of years. Between 430-380 million years ago a mountain range as tall as the current Himalayas was created in the north of Britain when two continental plates collided. When this mountain range began to be worn away, sand and grit was laid down by the erosion in a vast river delta that covered half of Yorkshire. The unusual shapes at Brimham Rocks are a result of more recent activity in geological terms. During the last ice age 18,000 years ago, glacial winds blowing off an ice cap that covered the Pennines carried tiny particles of sand and other debris. These winds often blasted the rocks at ground level which explains the strange mushroom shapes of many of them including the Idol Rock and the Druid’s Writing Desk.
The rocks at Brimham are gritstone which is sedimentary rock comprised primarily of sand and grit. Specifically, it is fluvial sedimentary rock which means it was formed by an ancient river system. The rocks show the flow of the sediment which is known as a bedding plain. During the ice age when a passing glacier created Nidderdale valley, the hard compressed millstone grit resisted this weathering and was left exposed as the soft rocks were cut away by the ice. The soft rock and shale was further affected by sand blasting and weather to leave the famous stacks of millstone grit. Wind, rain, and frost still attack the weaknesses in the rock. Some parts of the rock are quite soft and can be worn away by climbers.
Natural Brimham
Brimham is a site of special scientific interest (SSSI). In the summer the ground cover is awash with colour from the common heather and bell heather as well as the frutiting bilberry bushes, and cowberries. The area is home to a variety of wildlife such as solitary mining bees and green tiger beetle as well as various bird species such as the meadow pipits, red grouse and finches. Brimham as a landscape is among the rarest in the world which makes it a very special place to enjoy the varied and abundant wildlife in the area.
People at Brimham