0-25 



0-16 



tr. 



tr. 



2-20 



0-19 



56-11 



98-04 



42-48 



1-43 



101-04 



99-82 



5-54 



96-34 



93-05 



3-13 



238 ME. C. T. TEECHMA^X ON THE LITHOLOGT [June 1914, 



concretionary ' bluestones.' Towards the top of the quarry some 

 bands of a friable brown material (so-called ' marl ') appear 

 interbedded with the hard rock. This ' marl ' passes directly, 

 and with every gradation, into the ' bluestone.' I have seen lumps 

 of 'marl' with centres of 'bluestone.' 



XVII. Thinly and evenly-bedded, brown, friable material. When 

 dry it crumbles into a fine powder, of which 99*45 per cent, 

 passes through a sieve of 240 meshes per linear inch, leaving a small 

 residue (No. XVIII). Fossils occur as perfect impressions, 

 including mollusca, foraminifera, and plant-remains. 



XVIII. The residue from the above. 



XIX. 'Bluestone.' Fine-grained, grey, very hard, calcareous 

 rock. Fossils occur as obscure casts. 



XVII. XVIII. XIX. 



Insoluble residue 0*27 



Mn0 2 0-61 



Fe 2 3 , etc 0'59 



CaC0 3 56-44 



MgC0 3 42-54 



Totals 100-45 



Calcite 5-79 



Dolomite 93-19 



Flexible Limestones and Similar Beds. 



XX. Mars den. — Thinly-bedded, typical Flexible Limestone. 

 No fossils. 



XXI. Hesleden Dene. — A thinly-bedded, flaggy, fairly- 

 compact, yellow rock. No fossils. 



XXII. West Hartlepool Waterworks, from well-sinkings 

 at a depth of 49 feet A flaggy, extremely hard, rather absorbent, 

 yellow rock. No fossils. 



A section shows very small and irregular dolomite-grains, yellow 

 with ferruginous impurities. Calcite occurs locally. The quartz 

 fills much of the space between the dolomite-grains, which in 

 places develop rhombic outlines where they project into it. It 

 may be of secondary origin, or may be a recrystallized residue. 



XX. XXI. XXII. 



Insoluble residue. 6*70 3-16 42-65 (89-71 % SiO.,) 



Fe.,0 3 , etc 1*48 0'72 2-35 



CaC0 3 50-37 54'96 31-78 



MgC0 3 41-71 40-94 23-70 



S0 3 0-11 0-17 tr. 



Totals 100-37 99-95 100-48 



Calcite 0-71 6-22 3-57 



dolomite 91-37 89.68 51-91 



