[1] In the summer of 1907 the geologist Walther von Knebel, a friend and fellow student of Reck's, disappeared during a field trip in Iceland.

[1] Hans Reck was charged with determining what had happened, and set out in June 1908 with two local guides and his fiancé, Ina von Grumbkow.

[2] Reck and the Icelander Sigurður Sumarliðason were the first people ever to reach the summit of the Herðubreið volcano, 1,060 metres (3,480 ft) above the surrounding plain.

The Recks were assigned to follow up the 1911 expedition that had made a large collection of fossils at Tendaguru in German East Africa (now Tanzania).

[2] They reached Tendaguru in June 1912, rebuilt the camp and quickly settled into a routine of quarrying to collect dinosaur bones, helped by a large workforce of local people.

[7] Also in 1913, Reck made an ascent of the 2,960 metres (9,710 ft) Ol Doinyo Lengai volcano in the Gregory Rift, about 15 kilometres (9.3 mi) south of Lake Natron.

It described the geographic position of the volcano, history of explorations, geomorphological studies and gave a detailed account of the crater region, accompanied by photographs.

[8] In 1911 Wilhelm Kattwinkel, a German entomologist, had found interesting fossils in a ravine on the borders of the Serengeti Plains which turned out to contain the remains of a prehistoric three-toed horse.

[12] In June 1915 Reck discovered more Pleistocene fossils at a site close to Minjonjo, which he considered to have a similar age to those he had found at Olduvai.

[13] In June 1916 Reck turned over his field notes, personal valuables and the collection of pterosaur bones from Tendaguru to a Swiss railway engineer, who promised to take them to Switzerland if possible.

Inconclusive fighting continued for the rest of that year, with the allies handicapped by demolitions and suffering considerably from harsh conditions, disease and lack of supplies.

[16] Starting in 1917 the allies gradually began to gain the ascendancy, and by November 1917 the last Germans capable of leaving the country evacuated it for Portuguese East Africa.

[21][b] Reck had lost all his notes on Olduvai during World War I, but published a book of his first expedition in 1933 called The Ravine of Primeval Man.

[23] Hans Reck undertook a major study of the Santorini islands in the Aegean in 1936, working with Neuman van Padang and others.

[24] Reck was planning to prepare a detailed report on the 1913 and 1931 Olduvai findings, but first left on an expedition to Portuguese East Africa.