What is the difference between the formations of chalk versus chert? they are made of different source materials. they have different grain sizes. chalk is terrestrial; chert is marine. chalk is biochemical; chert is chemical?

The difference between formations of chalk versus chert is that they are made of different source materials.  Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes while Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk, chert formation can be either be of chemical or biological origin. 

The need activity of the nurse is to suction discharges from the trachea. current treatment approaches in the pressing consideration facilities or crisis offices are corticosteroids and nebulized epinephrine; steroids have demonstrated advantageous in extreme, direct, and even gentle croup. in the clear instances of croup, anti-microbials are not endorsed, as the etiology is viral