The most spectacular natural feature of Érd can be found in Ófalu: a steep promontory rises above the Danube, where the edge of the Mezőföld Plain ends like a tableland. The high bank breaks off towards the Danube at Ófalu as under-scoured vertical walls. The highest point on this plateau is Kakukk Hill (177 m), above Ófalu, but Sánc Hill (163 m) by the Danube is more striking. The mean altitude of the Danube surface at Érd is just under 100 m, so that the high river bank rises about 60 m above the water surface. Here a decisive part in shaping the contours has been played by the river, which still reaches the foot of the high river bank in times of high water. There have been land slips and landslides in several places, incidentally providing insight into the geology of the high bank.
 
The high bank at Érd has been wrongly calles a loess wall, for there are loess walls further downsream (at Dunaföldvár, Paks and Rácalmás). But loess is homogenous, whereas the high bank at Érd has clearly apparent strata of clay, sand and marl. These are a much older formation than the wind-borne loess, which is only found in the district in small, isolated patches. The high bank was formed 5-6 mn years ago by sediment from the freshwater Pannonian Sea. In fact it is one of the finest examples in Hungary of a formation of the Pannonian stage (or more precisely, the Pontian layer of the Upper Miocene). At the end of the Tertiary, as the sea covering the Carpathian Basin steadily sweetened, layers of clay accumulated out of material washed down from the mountains ringing the basin and sediment from the Pannonia Sea itself. Further south, this series of sedimentary layers is less thick, as the faults gradually sank them into the ground.
 
An important part in the formation and survival of the high bank at Érd was played by the strata of harder calcareous marl, whose greater resistance to erosion shielded the softer layers of sand and clay beneath. Where these marl layers have collapsed, boulders of it several meters round can be seen beside the Danube and the footpath from Ófalu to Százhalombatta. The sandy layers of the Pannonian sediments contain shells of the mollusc Unio wetzleri, with interesting petrified remains inside them. This early mollusc resembles a species surviving today, Unio pictorum, whose oval shells 5-8 cm long can be found in the gravel on the banks of the Danube (The Latin name refers, to the use of the shells by painters to mix water colours.) Living in rivers and streams north of the Alps, its shells are carried down by the current of the Danube.
 
The length of the high bank at Érd that runs above the Danube is particularly exposed to erosion and land slips, while the side overlooking Ófalu is now bound together by grass and in some parts trees and shrubs. Sheltering under the walls in an unusual vegetation, with associations of Eastern puszta and steppe plants with relics of Mediterannean vegetation that arrived from the south after the last Ice Age. A thorough study of the flora of the high bank at Érd was made in 1944 by Ádám Boos, who described Artemisia austriaca and A. pontica (relatives of wormwood), the campion Silene longiflora, yellow flax (Linium flavum), and specimens of several other plants. Typical of the high bank at Érd is the way reed (Phragmites vulgaris) and the large-leafed composite coltsfoot (Tussilago farfara) can be found clinging high up where water seeps out of the slope. The geological and botanical specialities of the high bank at Érd, coupled with the early Iron Age finds above it, led to a protection order in 1985.