208 SCIENCE PROGRESS 



protein hydrolysis by this means. After 192 hours' boihng, 

 over 90 per cent, of the sulphur remainder in the unchanged 

 form, traces of sulphuretted hydrogen and free sulphur being 

 formed from the fraction decomposed. Intramolecular changes 

 appeared to have occurred in the cystine, however, for its 

 precipitability by phosphotungstic acid and its optical rotation 

 both became less. From the residual hydrolysate an isomeric 

 cystine was isolated which crystallised in small microscopic 

 prisms and showed different physical and chemical properties. 

 It was optically inactive. A number of derivatives of the 

 two forms of cystine were prepared, and in every case those 

 prepared from the isomeric form differed from those prepared 

 from the natural " plate " cystine. The authors suggest that 

 the isomeric form is identical with the s^mthetic cystine pre- 

 pared by Fischer and Raske and by Erlenmeyer and Stoop, 

 and that " plate " cystine obtained from protein hydrolysis 

 has never been synthesised. 



GEOLOGY. By G. W. Tyrrell, F.G.S., A.R.C.S., University, Glasgow. 



Orogeny and Highland Tectonics. — A highly significant view of 

 erogenic processes is developed by R. T. Chamberlin in a paper 

 on " The Building of the Colorado Rockies " {Journ. GeoL, 27, 

 1919, 145-64, 225-51), wherein he compares and contrasts a 

 thick-shelled mountain range such as the Colorado Rockies with 

 a thin-shelled range of the type of the Pennsylvanian Appala- 

 chians. Thick-shelled mountains are characterised by open 

 gentle folding, moderate crustal shortening affecting a rela- 

 tively deep zone, and by strong uplift with vertical movement 

 and normal faulting. In thin-shelled mountains a relatively 

 thin superficial portion of the crust has been affected by intense 

 deformation, leading to great overthrusting especially in the 

 marginal parts of the ranges. Horizontal movement is dominant 

 in this type. 



The building of the deep-rooted Colorado mountains was 

 accompanied by the extrusion of great masses of lava, whilst 

 this feature was not at all prominent in the Appalachians. 

 Even in different parts of the Rocky Mountains analogous 

 differences appear. In Colorado, where the deformed zone is 

 deep and there has been a large vertical movement, lava flows 

 have occurred in abundance ; in the Canadian Rockies, how- 

 ever, where the deformed zone was much shallower, and suffered 

 intense horizontal thrust, but little volcanic activity took 

 place. 



In a supplementary paper {Journ. GeoL, 29, 1921, 166-72), 

 Chamberlin extends the comparison of thick-shelled and thin- 

 shelled mountains in regard to intrusive activity also. Little 



