MICHIGAN ACADEMY OF SCIENCE. 
E9 
Delray, but 7 are in common to these, one only of which is found in 
the dolomite of the Detroit river bed in the vicinity of Amherstburg. 
Having presented * evidence to show what the Anderdon limestone beds 
are not, I shall attempt to show wliat these beds are, — how they are 
deposited, and how they are related. 
THE MALDEN VALLEY. 
The drill holes put down to determine the extent of the Anderdon 
limestone have disclosed a basin and a valley leading to it from the 
south, together containing the “Anderdon Beds” (Grabau). I have pre- 
sumed to name this valley the Malden Valley of the Anderdon Lime- 
stone, inasmuch as it was first followed up from a starting point in 
Malden township. T have followed up this valley some 6,500 feet from 
that starting point of investigation to where it expands into a basin, 
the central area of which is the Amherstburg Quarry property. 
Cross sections prove the valley formation and show the relation of the 
Anderdon Beds to the underlying Silurian dolomites. A complete cross 
section is constituted by test holes numbered 9 to 13, from east to west. 
In No. 9, in an old Detroit river channel, there is a Silurian surface 
extension. Analvses show an average of 56.75 CaCCL. 
About 800 feet west of it No. 10 showed Anderdon Beds at the sur- 
face, one foot in depth, resting upon a transitional rock, which in turn 
rests upon Silurian dolomite. The transitional here averages 60.56 
CaCCL, and is 8 feet in depth ; the dolomite 54.19 tested to a depth of 21 
feet. 
No. 11 is about 700 feet west of No. 10: Anderdon 13 feet, averaging 
93.76 CaC0 3 ; Transitional, 8' 6", 63.37; Silurian dolomite 5' 10", 54.87. 
No. 12, about 700 feet west of No. 11, shows 10' 7" of Anderdon, 
averaging 95.60 CaC0 3 ; Transitional, 7' 9", 62.44 ; dolomite not pene- 
trated. 
No. 13 is about 700 feet of No. 12. Here there is but 2 feet of Ander- 
don Beds, averaging 94.72 CaCCL; Transitional 7' 5", averaging 57.53; 
Silurian dolomite penetrated 11' 7", averaging 50.39 CaCCL. 
Some 6,000 feet west of No. 13 is the Detroit river bed, with Silurian 
dolomite extension, — a surface that would probably extend as a surface 
extension as far east of Detroit river as to a point 300' to 400' west 
of No. 13 test hole. 
A review of this cross section shows : 
(1) The Anderdon Beds in the Malden Valley banking up against 
Silurian dolomite, east and west; 
(2) A Silurian surface extension both east and west of the Anderdon 
Beds, in the old Detroit river channel eastward and in the bed of the 
present Detroit river westward ; and, on reference to elevations, 
(3) A Silurian dolomite synclinal between the Canadian channel of 
Detroit river immediately opposite Amherstburg (elevation 552.5 -{-) 
and No. II) test hole, (elevation of Silurian surface, 563.2) in close prox- 
imity to the eastern edge of the Anderdon ; 
(4) A similar syncline east of that again, immediately; (5) Dis- 
turbance of former levels prevailing during the time of depositing of the 
*See Michigan Academy of Science report, 1910. “The Contour of the Sylvania Sar.drcck and 
Related_Strata in the_Detroit River Area.” 
