Botryococcus to macerals in several unmacerated coal 

 samples. The scope of the petrographic study did not 

 include analysis of all coals containing Botryococcus nor 

 the particular parts of the beds that contain the alga. 

 Thus, we cannot determine which layers within the coal 

 beds would be classified as boghead coal. 



The composition and origin of boghead coals and 

 related torbanites have been discussed in detail by Thies- 

 sen (1925), Blackburn and Temperley (1936), and Allen 

 et al. (1980). These publications summarized the no- 

 menclature of algal coals and shales and the history of 

 the investigations. Boghead coal, bituminous shale, 

 cannel coal, torbanite (black oil shale), and other rocks 

 containing algae have not been satisfactorily classified. 

 Schopf (1949) noted that boghead coal, which is non- 

 banded, is composed mainly of algae but often contains 

 some spores. Cannel coal, which is also nonbanded, 

 mainly contains spores but may also contain algae. 

 Occasional colonies of Botryococcus may also be present 

 in attrital portions of banded coals. 



Morphology and Ecology of Botryococcus 



Modern Botryococcus is planktonic and widely distrib- 

 uted in temperate and tropical climatic zones through- 

 out the world. It occurs in permanent to semipermanent 

 freshwater pools and lakes, but occasionally it grows in 

 salt water. Some species live in still water, and others 

 live in moving water. Botryococcus has also been found 

 in peat (Blackburn and Temperley 1936). The presence 

 of starch in living Botryococcus places it among the 

 green algae (Chlorophyceae), but the structure of cell 

 walls and color of the plastids are characteristic of yel- 

 low-green algae. Cells produce large amounts of oil. 



Modern Botryococcus forms free-floating, amor- 

 phous colonies enclosed in a cartilaginous green or orange, 

 wrinkled and folded envelope. The closely spaced, 

 ovoid or cunate cells usually occur in groups of multi- 

 ples of two in a single layer toward the edge of the 

 colony (fig. 1). The cell groups are radially arranged 

 and connected by broad, delicate strands. 



Cell walls are transversely divided into two un- 

 equal overlapping parts, with the lower part being 

 longer. A cell is enclosed within a waxy thimble, which 

 itself is partly enclosed within a fatty cup that has a 

 stalk- like projection into the center of the colony (fig. 1). 

 Cells reproduce by longitudinal division. The resulting 

 cells produce new thimbles and cups within the old 

 ones; the lower part of the cell forms the new cup. 



After the algae die, the cells usually decompose, 

 but the waxy-fatty skeletons of the colony are usually 

 preserved. Fossil Botryococcus consist of the skeletons as 

 modified by sedimentation and coalification (Traverse 

 1955, Smith 1950). 



Bertrand and Renault (1892, 1893) collaborated for 

 over 20 years in studying algal coals and shales. Renault 

 (1899-1900) concluded that boghead coals were formed 

 in swamps, lakes, and pools as an organic jell that had 

 been altered by microorganisms. Spores, cuticles, plant 

 cells, and debris were suspended in the jell. However, 

 Bertrand and Renault's explanation was not widely 



accepted because they proposed that bitumen from an- 

 other source infiltrated the matrix and did not specify 

 an alga that matched the characteristics of boghead 

 algae. Jeffrey (1910) suggested that the algae are spores. 



Zalessky (1914) described the rubbery oil deposits 

 produced by Botryococcus braunii in shallow parts of a 

 present-day lake in Turkistan. The algal colonies in the 

 oil mass, as seen in thin sections, resemble the colonies 

 of algae in boghead coals. Zalessky (1926) also identi- 

 fied B. braunii in balkhashite, the sapropelic rock of 

 Russia. Thiessen (1925) described living algae in salt 

 lakes and lagoons in South Australia and showed that 

 they are closely related or identical to the algae in 

 boghead coals. He stated they resembled blue-green 

 algae in some respects but was not certain of their 

 affinity. He proposed the name Elaeophyton for what are 

 actually colonies of Botryococcus. Blackburn and Tem- 

 perley (1936) described in detail the algae from 

 boghead coals and showed that the fossil forms of 

 boghead algae are closely related to modern B. braunii. 

 Niklas and Phillips (1974) and Niklas (1976) correlated 

 fossil boghead algae and living Botryococcus by compar- 

 ing microchemical compositions and morphologies. 



Dulhunty (1944) studied a Permian torbanite in 

 New South Wales and proposed that deposits of Botryo- 

 coccus do not form in peat swamps that contain abun- 

 dant humic matter. He suggested the water, which 

 contained dissolved humic and mineral matter, flowed 

 from swamps and marshes into lakes. No vegetation, 

 except for algae, was established in the lakes because 

 the water level frequently fluctuated. Moore (1968) be- 

 lieved that algae probably lived toward the center of 

 lakes where sufficient oxygen was available because 

 organic matter would be most abundant around the 

 margins of the lakes. The association of Botryococcus 

 with opaque attritus in coal led Schopf (1952) to con- 

 clude that the attritus had formed under moist rather 

 than dry conditions, as previously presumed. 



Since the vitrinite in the boghead coal at the top of 

 the Tarter Coal Member occurs in very thin bands, 

 Kosanke (1951) concluded that the freshwater peat bog 

 did not support many arborescent plants. He sug- 

 gested, however, that the upper part of the Tarter Coal 

 might not be a true boghead because of the large per- 

 centage (24%) of vitrinite. He macerated some of the 

 coal, but isolated individual colonies showed little 

 structure. 



Bradley (1966) described the sediment in Mud 

 Lake, Florida, a modern analog to oil shale. The sedi- 

 ment contains a layer of ooze made up of abundant 

 Botryococcus that slowly accumulates about 3 feet below 

 the water-mud contact of the shallow lake. Fecal pellets 

 containing remains of algae are common in the ooze, 

 and plant debris is rare. At greater depths, after having 

 depleted the available nutrients from the mud, the al- 

 gae produce oil, fats, and pigments. 



Dulhunty (1944, p. 32) remarked that "the very 

 primitive nature of the living Botryococcus suggests that 

 the organism has not changed for a very long time, and 

 justifies the belief that it has descended from the late 



