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= Hadar Formation = The Pliocene Hadar Formation is a geologic unit that was deposited about 3 million years ago in the Afar Triangle of Ethiopia. The formation is remarkable for the many fossil hominid specimens that it contains. The most famous of which is the iconic Australopithicus afarensis specimen 'Lucy'.

Location
Geographically, the Hadar Formation is contained within the Afar Region of Ethiopia. From a geologic context, the Hadar Formation is located in the Afar Triangle which is at the northern end of the East African Rift Valley. The Hadar Formation crops out of the plains in the Awash River Valley.

Stratigraphy
The Hadar Formation comprises the region's sedimentary sequences from 3.4 - 2.3 Ma. These strata are comprised primarily of paleosols that were deposited in floodplains, sands and sandstone deposited in river deltas, and lacustrine clays, and diatomite beds of deep lake phases. The Hadar Formation is divided into four members that are divided by prominent volcanic tuff layers. The Basal Member lies directly on top of the Afar basalts that are 4.5 Ma. The top of the Basal member is defined by the Sidi Hakoma Tuff and is dated to 3.4 Ma. The Sidi Hakoma Member overlies the Basal Member and is capped by the Triple Tuff which is dated to 3.22 Ma. The Denen Dora member lies above the Triple Tuff and is capped by the Kada Hadar Tuff which is dated to 3.175 Ma. The Kada Hadar Member lies on top of the Kada Hadar Tuff. The Kada Hadar Member contained AL 288-1 'Lucy'. The top of the Kada Hadar Member is loosely defined as being capped by conglomerate beds with prominent tuff layers that are dated to ~2.3 Ma. These conglomerate beds tend to lay unconformably on the Hadar Formation. The unconformity at the top of the Hadar Formation makes it difficult to document the geologic history of this area from ~2.9 - 2.3 Ma. Recent investigation has suggested that the Busidima Formation may directly overlay the Hadar Formation. The Busidima Formation has been dated to ~2.7 Ma.

Paleontology
Floral and faunal lists of the organisms that were fossilized and have been recovered and cateloged from the Hadar Formation are compiled below. These species represent a small fraction of the organisms that would have lived in the region at the time the Hadar Formation sediments were being deposited. Ongoing research in the region is sure to reveal more species each season. this list is neither comprehensive nor up-to-date.

Flora
 Phylum : Bacillariophyta

Class: Cosconodiscophyceae

Order: Aulacoseirales

Family: Aulacoseiraceae


 * Aulacoseira granulata
 * Aulacosiera helianthus
 * Aulacoseira jewsonii

Order: Coscinodiscales

Family: Coscinodiscaceae


 * Lindavia cohenii

Fauna
 Phylum : Chordata

Class: Mammalia

Order: Artiodactyla

Family: Bovidae


 * Syncerus
 * Tragelaphus sp.
 * Cephalophini sp.
 * Hippotragini sp.
 * Reduncini sp.
 * Parmularius sp.
 * Beatragus sp.
 * Raphicerus sp.
 * Gazella sp.
 * Gazella praethomsoni

Family: Giraffidae


 * Giraffa sp.

Family: Suidae


 * Metridiochoerus modestus
 * Kolpochoerus limnetes

Order: Carnivora

Family: Herpestridae


 * Herpestes sp.

Order: Primates

Family: Cercopithecidae


 * Cercopithecoides kimeui
 * Parapapio jonesi
 * Theropithecus oswaldi

Family: Hominidae


 * Australopithecus afarensis
 * Homo sp.

Order: Proboscicea

Family: Eliphantidae


 * Palaeoloxodon recki atavus

Order: Rodentia

Family: Thryonomidae


 * Thryonomys swinderianus

Family: Hystricidae


 * Hystrix cristatus

Family: Muridae


 * Golunda gurai
 * Millardia coppensi

Class: Reptilia

Order: Crocodilia

Family: Gavialidae


 * Kentisuchus sp.

Archeology
Stone tools found in the Hadar Formation are characteristic of and classified as Oldowan. In the Hadar formation they are made from volcanic and sedimentary rocks, typically that of chert and basalt. The source of these tools tend to be from cobble sized river rocks.