366 NATURAL SCIENCE. 



June, 



which cross its outcrop, but run for only a small portion of the year. 

 The Desert Sandstone is also very absorbent, and where it " lies like 

 a full sponge on the top. ... of the Blythesdale Braystone, must 

 tend to equalise the supply by feeding the latter long after the rivers 

 have ceased to run." There is also evidence that the sandy beds d, f, 

 and f 1 of the diagram may abut in places on the Blythesdale 

 Braystone, and still further tend to equalise the supply. These 

 auxiliary beds are of greater importance if it be the case, as some 

 suppose, that the Blythesdale Braystone crops out on the sea-floor, 

 and thus parts with some of its fresh water by leakage into the ocean. 

 In any case it appears, from the figures collected by Mr. Jack, that 

 the amount of water passing through this bibulous bed is far more 

 than can ever be exhausted by artificial means, so that the multipli- 

 cation of bores is not a danger to be dreaded, but a remedial measure 

 to be urged on by all means. We hope that Queensland will 

 support its Geological Survey, which has made its deserts blossom 

 like the rose. 



Niagara and the Great Lakes. 



So much has been written on Niagara Gorge and the Great 

 Lakes, without exhausting the subject, that we venture to bring 

 before English geologists the conclusions arrived at by Mr. Frank 

 Bursley Taylor, and published by him in The American Journal of 

 Science for April. We reprint here merely his chronological conspec- 

 tus, and must refer our readers to his paper for the details of the 

 various steps, so concisely set down by him, and so easily followed by 

 anyone who troubles to read the conspectus with a map in front of 

 him. 



Mr. Taylor says : — " At its maximum the great Laurentide glacier 

 covered the whole area of the Great Lakes. By a correlation of the 

 abandoned shore lines, moraines and outlets, and the gorges, recently 

 submerged shore lines and rivers of this region, the following order of 

 events is made out for the post-glacial history of the Great Lakes. 

 They are set down in seven principal stages, with transitions or 

 critical stages between. 



" I. Glacial, ice-dammed lakes. Outlets at Fort Wayne, Chicago, 

 and other places. Beaches correlated with moraines in Ohio. 

 Glacial lakes fall by stages as outlets change on withdrawal of the 

 glacier-dams. Land relatively high in the north but slowly subsiding. 



" First Transition : By withdrawal of glacier the Niagara river is 

 opened and the upper lakes become united. 



" II. First Niagara lakes. First epoch of Niagara Falls begins 

 at Lewiston. For a short time glacial Lake Iroquois receives the 

 water from Niagara. Shore lines of lower levels of this glacial lake 

 washed over and obliterated by later marine invasion. Gradual 

 depression of land continues at north, finally opening Nipissing 

 outlet. 



