AS everybody who has ever studied basic geography at school knows, there are just three main types of rock making up the Earth's land surface - igneous, metamorphic and sedimentary.

All three types are found in and around Great Malvern. The Malvern Hills themselves are mainly made of igneous rocks, which were formed deep inside the Earth's core and then later thrust to the surface. At Tank Quarry, in North Malvern, there is a short geological trail with examples of the different rock types. It forms an interesting appetiser to a walk in the lovely area to the north-west of the Malvern Hills.

A path also leads to the quarry shelf; and while there is no actual access to the quarry, there is a good view of it. The rock which forms Tank Quarry is mostly 600 million-year-old diorite, an igneous rock which is dark-grey in colour and full of minerals.

It's known commercially as black granite. Igneous rocks are very hard and resistant to erosion, which is why the Malverns rise so dramatically above the sedimentary sandstones which lie to the east. These softer rocks were laid down in desert conditions around 300 million years ago and have since been heavily eroded.

Metamorphic rocks began life as igneous ones but were later changed by extreme heat and pressure, and many of the rocks at the southern end of the Malverns fall into this category. This walk, however, is confined to the igneous rocks of the northern Malverns and the sedimentary limestones which form the small but scenic hills to the west.

DIRECTIONS

1 Leave Tank Quarry and turn left along North Malvern Road (which becomes West Malvern Road), following signs for the Worcestershire Way, which quite soon leaves the road, descending steeply to another road. Turn right, signed 'Worcestershire Way North', and then soon left, leaving the road. Descend quite steeply to Cowleigh Road, cross over and turn left.

2The Worcestershire Way leaves Cowleigh Road just after The Byre and runs through fields and orchards to cross a footbridge. Proceed a few paces further to a fence corner where two paths are waymarked. Leave the Worcestershire Way and take the path heading left. There are two hills ahead: the one on the right is bare apart from a handful of trees, while the one on the left is crowned by woodland (Rough Hill Wood). You'll see a track running between the two hills, and you should head for this, meeting it at a waymarked junction. Follow the track uphill, with Rough Hill Wood on your left. After passing through a gate, the track runs closer to the woodland edge at first and then moves away from it, past orchards. Fork right as you approach Hill Farm, passing close by the farmhouse, then turn sharp right and follow the waymarked path down to Crumpton Hill Road.

3Turn left, then cross the main road (B4219) and climb to the top of Whitman's Hill. Enter woodland and turn left on a path running along the top of the ridge. After a short distance the right of way leaves the wood, runs along a field edge and then returns to the wood (while an unofficial but well-used path stays within the wood instead). Keep straight on at all junctions, keeping to the ridge-top. Eventually you will have to leave the wood and proceed to Croft Farm. Turn left and walk to a road.

4 Turn left, then keep straight on up Croft Bank at a junction with Mathon Road. Cross West Malvern Road and walk up Westminster Bank, passing Westminster House, Anstruther Hall and Bank House. Continue to a junction near a wooden bench and a spring, and turn left on a wide track. Shortly turn right by a gas lamp, passing a memorial bench and a stone waymarker indicating Great Malvern. Walk up to the spine of the Malverns, go forward to meet a bench and then turn left, past gorse bushes, until you come to a cross-path. Go straight on, descending to join a wide track (Lady Howard de Walden Drive) near a memorial bench. Turn left, ignoring branching paths.

5You'll eventually reach a junction where a path descends right to North Quarry. Keep left on the higher path, then do the same again at the next junction (unless you came by bus, and would like a short-cut: if so, descend to the Link Top bus stop, which is visible almost directly below). The higher path climbs slightly, passes a fenced area and then levels out. Take a narrow path on the right, descending past some gorse bushes and keeping straight on at a cross-path. Head towards a tall, fire-damaged ash tree, with several fallen limbs lying on the ground. Turn right when you reach the tree and descend to meet the road near Tank Quarry.

FACTFILE

Start: Tank Quarry, North Malvern Road (B4232), grid ref SO770470.

Length: 4 miles/6.5km.

Maps: OS Explorer 190 or OS Landranger 150 (Harvey Superwalker Malvern Hills shows part of the route).

Terrain: Malvern Hills, with nearby orchard, pasture and woodland; steep in places.

Footpaths: Excellent.

Stiles: Six.

Parking: Tank Quarry Picnic Place.

Buses: First 44 operates daily to Great Malvern and Link Top. You could change at Great Malvern to Newbury Coaches 675 for Tank Quarry, but it's simpler just to take the 44 to Link Top, which is only a short walk from the quarry - cross the Leigh Sinton road then walk up Trinity Road to North Malvern Road; www.traveline.org.uk or 0870 608 2608.

Refreshments: Knights Cider shop (when open).

PLEASE NOTE This walk has been carefully checked and the details are believed to be accurate at the time of publication. No responsibility is accepted by either the author or publisher for errors or omissions, or for any loss, accident or injury, however caused.