Not quarried in Purbeck on such a scale as ball clay, chalk was gathered from the ridge of hills  which run from the coast at Swanage, through to Weymouth. 

Chalk is an excellent material for hardcore and light road building and was used for Clay mining access roads. (The Foreman's Office at the museum sits on one of those roads, which served the Norden Works)

In earlier times decayed chalk (known as Marl) was burned in kilns to produce lime for mortar and soil conditioning. Much of the Purbeck heathland was reclaimed for agriculture using the limes. The remains of a kiln can still be seen on the hillside at Church Knowle.

At Cocknowle there was an inclined tramway taking Marl from the Pit at the top of the hill down to the road. This pit was worked by Thomas Page Powell who owned the Wareham Cement woks at Ridge. The Marl was used by them to produce "Portland Cement" and and various limes for both building and agriculture purposes.

In 1881 Dorset County Chronicle visited the Wareham Cement works and reported thus.

"The Marl is passed through a mortar pan and worked into a plastic state, then it is mixed with a dry ground marl and put through a pug mill, coming out in the shape of bricks, which are wheeled into the yard and stacked on racks for drying. There are four kilns used for burning these bricks, which are laid alternatively with coke, taking about thirty hours in the process, during which the bricks become reduced about a third in weight and rendered into clinkers. These are passed through a Blake's crusher and reduced to the size of walnuts. This is raised to the hopperbox above the mill stones by means of an elevator.
    I am told that the sieve, through which all the cement passes, has 1600 meshes to the square inch. That which does not come up to the crucial test passes below to a small pair of stones, and is carried up again to the sieve. After undergoing this process it is run down into bins to the floor below. Here there is a very large stack in bulk, as well as on the ground floor, and it is this that the men are weighing into bags and putting into casks ready to be sent away. 
    The machinery is worked by a powerful horizontal condensing engine, the flywheel of which weighs four tons and measure twelve feet in diameter. This and the double flue Cornish boiler was supplied by Messers Lewin of Poole. The qualities of this cement were afterwards tested with a Michele's machine - the briquetts were placed in it. The first (two months old) stood the test of 1400lb. to the 1¹/₂ inch by 1¹/₂ inch section. One at one month broke at 1000lb. and the third (only 6 days old) stood the test of 1000lb and did not break. All these were immersed in water when only a day old. This I believe, Is equal to any cement that is made, being considerably beyond Government requirements, and is spoken of in a number or testimonials."

The advert below states that Thomas Page Powell supplied Railway Companies and it could be possible that a couple of years after the above visit to the works, cement was supplied for the building of skew bridge at Norden. If so the bridge demonstrates the high quality of cement produced. The skew bridge at Norden is 125 years old at the time of writing (2008) and is still structurally sound. 

An advertisement for the Wareham Cement Works in the Wareham Town Hall Museum (Well worth a visit)

Below is a list of the workers employed in the Purbeck cement industry from the 1881 Census