286 ANNUAL. REPORT SMITHSONIAN INSTITUTION, 19 38 



citrate. The mineral has been named "Earlandite" in honor of the 

 distinguished worker on foraminifera, who found them among the 

 organic remains in samples he was examining. As calcium citrate 

 has been found in plants, the presence of impurities such as Sr, Ba, 

 Mg, Mn, Fe, and Cu in the crystals may be significant They came 

 from a depth of 1,410 fathoms and are of very restricted distribution; 

 their origin is conjectural. Bannister and Hey also found crystals of 

 gypsum (CaS0 4 .2H 2 0) in samples collected by the Discovery in the 

 Weddell Sea in 1925, from a depth of 2,800 fathoms. These gypsum 

 crystals are of lenticular form up to 2 mm in length. Although they 

 have not previously been found in oceanic deposits, they have been 

 known for many years to be authigenic constituents of the muds of 

 the Mersey Estuary. Their formation in the Weddell Sea, like that 

 of the two new minerals mentioned, points to peculiar conditions, 

 perhaps of deep-sea lagoonal character. 



In review, we see in the history of the earth the operation of 

 repetitions of the geological cycle of rock-erosion (earth-sculpture), 

 transport and deposition of sediment, and earth movement leading 

 to uplift. The interaction of the atmosphere, hydrosphere, and 

 lithosphere, assisted by the thermal energy of the sun and the 

 gravitational influence of the moon, results in the disintegrating 

 work of frost, rain, wind, changes of temperature, and the waves. 

 The geologists' music of the spheres, though not without harmony, 

 resolves itself into two clear refrains — of degradation on the surface 

 of the exposed earth crust, and synthesis on the sea floor. But the 

 process of reconstruction is effected with impoverished materials, for 

 the decomposition of rocks and minerals proceeds both mechanically 

 and chemically, and the soluble products pass out of the geological 

 cycle to a considerable extent by accumulating in ocean waters. All 

 the known chemical elements are doubtless present in solution in the 

 sea, but whilst calcium, silicon, iron, phosphorus, copper, and others 

 are extracted to a greater or less extent by organisms, elements such 

 as sodium, chlorine, and nitrogen accumulate. Against this increasing 

 salinity of the sea, we must set off the formation of authigenic min- 

 erals on the sea floor, but we have no reason for thinking that this 

 process bulks largely. A certain amount of compensation for the 

 loss of soluble materials from the geological cycle is afforded by the 

 delivery from subcrustal reservoirs of new rock material by volcanic 

 action, but we have no means of assessing its effect in restoring the 

 balance. 



Prediction is dangerous, but we may go so far as to ask ourselves 

 whether the pointers in geology are suggestive of an irreversible 

 trend to an uninteresting uniformity. On the earth's crust, the 

 breaking-down of minerals and rocks, many of which are complex 

 silicates, results in the liberation of the elements which form more 



