The formation and geological folding of the Harz hills began during a prominent phase of the Palaeozoic era, in the course of the Hercynian mountain building of the Carboniferous period, about 350 to 250 million years ago.

During times of decay and rejuvenation when there is plenty of light, light-dependent pioneers such as rowan (Sorbus aucuparia), silver birch (Betula pendula) and pussy willow (Salix caprea) play a role.

Melic grass beech woods are found in the few places where there is an abundance of nutrients and bases, e. g. over dolerite and gneiss formations, and they have a vegetation layer rich in variety and luxuriant growth.

Here, too, the common beech dominates, mixed, for example, with sycamore, ash (Fraxinus excelsior), hornbeam (Carpinus betulus) and Scots elm (Ulmus glabra).

At intermediate heights of between 700 and 800 m above sea level, mixed woods of spruce (Picea abies) and common beech would predominantly be found under natural conditions.

A well developed ground vegetation thrives on their moderately rocky and fresh, but certainly not wet, soils, characterised in appearance especially by grasses such as shaggy wood-reed (Calamagrostis villosa) and wavy hair-grass (Avenella flexuosa).

The soils in the higher regions are, as in most of the Harz, comparatively poor in nutrients and bases, so that only a few herbaceous plants occur here, such as heath bedstraw (Galium saxatile).

They have an especially high variety of trees and allow more room of light-loving species such as silver birch, rowan, sycamore, willow and dwarf bushes such as the blueberry (Vaccinium myrtillus).

Typical grasses are the sheathed cottongrass (Eriophorum vaginatum), known for its bright, white clusters of fruit and deergrass (Scirpus cespitosus), which is rust-red in the autumn.

This shy and susceptible resident of richly diverse deciduous and mixed forest has become very rare in central Europe due to increasing disturbance of its habitat (caused by a lack of old trees and natural brooks).

Special mention should be made here of the pygmy owl (Glaucidium passerinum) which is threatened with extinction and which lives in the submontane to subalpine zones within mixed and pine forests interspersed with open areas.

Examples of these are the Alpine emerald dragonfly (Somatochlora alpestris), which only occurs in Lower Saxony in the Harz, and is endangered in Germany, and the Subarctic darner (Aeshna subarctica), a damselfly which is threatened with extinction.

The Upper Palaeolithic Revolution, about 40,000 years ago, saw Homo sapiens move from Africa into Europe, including to the Harz region, where they appear to have ousted the Neanderthals and subsequently settled here.

The Saxon Mirror (Sachsenspiegel), the oldest German law book (Rechtsbuch), probably published around 1220/30 at Falkenstein Castle in the Selke valley, later made the imperial restriction clear: "Whoever rides through the Harz Forest, must unstring his bow and crossbow and keep dogs on a line – only crowned royalty (gekrönte Häupter) are allowed to hunt here".

Eike von Repkow's Sachsenspiegel which, for centuries, formed the basis on which German law was administered, described the Harz as a place where wild animals are guaranteed protection in the king's restricted forests.

Mining, ironworks, water management, increasing settlement, woodland clearances, cattle driving, agriculture, and later tourism all undermined this imperial protection over the centuries.

As early as 1224, monks who had settled in Walkenried bought extensive tracts of forest in the western Harz, to secure economically the one quarter of the Rammelsberg ore profits promised to them by Frederick Barbarossa in 1129.

The less resistant spruce monoculture, that arose as a consequence of the mining industry in the Upper Harz, was largely destroyed by a bark beetle outbreak and a storm of hurricane proportions in November 1800.

By 1912, he effectively pressed for the establishment of a Harz national park, without calling it such, in Der Harzer Heimatspark (Verlag E. Appelhans u. Co., Braunschweig 1912), a brochure that has remained relatively unknown.

The Wernigerode rector, W. Voigt, wrote, in 1926, in his famous Brockenbuch: In America it has long become the business of the people, to create a sacrosanct haven for the native flora and fauna of the regions in national parks.

There were concrete plans for the national parks of the Lüneburg Heath, Bavarian – Bohemian Forest, High Tauern, Höllengebirge, Neusiedler See and Kurische Nehrung.

When the United States First Army reached Nordhausen in the southern Harz, and went to advance northwards, it met with resistance, especially in the hills around the towns of Ilfeld and Ellrich.

Shortly before his death in 2003, American Second World War veteran and organized crime figure, Frank Sheeran, admitted to having participated in a massacre of German POWs in the Harz area.

[3] Wernher von Braun, one of the leading figures in the development of rocket technology in Germany during the Second World War and, subsequently, in the United States, reportedly ordered blueprints of his work to be hidden in an abandoned mine shaft in the Harz range.

With the closure of this facility, mining operations that had begun in the Middle Ages and had continued unbroken since the 16th century, extracting silver, lead and zinc, came to an end.

In Bad Lauterberg, barite – used today primarily for the manufacture of paint and in sound insulation – was extracted until July 2007 at the Wolkenhügel Pit, the last mine in the entire Harz.

The reforestation with relatively easily managed and undemanding spruce trees since the middle of the 18th century was mainly due to the proposals of the Senior Forester and Master Hunter, Johann Georg von Langen.

Their quality and features are ensured by the land owners, particularly in the Harz National Park, where snow is still relatively guaranteed during the winter months, and also by individual communities and societies.

The mountain rescue service on the cross-country routes, the toboggan slopes, footpaths, alpine ski pistes and rough terrain is provided by the Bergwacht Harz.

Prior to the closure of the Inner German border the present-day network was joined at Sorge to the Südharzbahn (South Harz Railway), which ran from Walkenried to Braunlage and Tanne.