| Computer Code: |
KNCK |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Turonian Age (KT)
— Coniacian Age (KO) |
| Lithological Description: |
Very hard nodular chalk and chalkstone, including mineralized hardground surfaces. |
| Definition of Lower Boundary: |
The lower boundary is conformable at the top of the Chalk Rock Member above the flint nodule horizon that marks the top of the Hitchwood Hardground. |
| Definition of Upper Boundary: |
The upper boundary is conformable at the top of obviously indurated chalks near the base of the Lewes Nodular Chalk Formation ("Upper Chalk") but overlying the Chalk Rock Member. Note that this does not necessarily coincide with the top of the Top Rock. |
| Thickness: |
c. 2.5 to c. 4 m in the Hitchin and Leighton Buzzard districts. |
| Geographical Limits: |
Known within the Leighton Buzzard and Hitchin areas of the Chilterns. |
| Parent Unit: |
Lewes Nodular Chalk Formation (LECH)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Kensworth Chalk Quarry, near Dunstable, Bedfordshire. Full succession of four glauconitized hardgrounds is visible on quarry faces above prominent Chalk Rock Member. |
| Reference Section |
Reed Chalk Pit, south of Royston, Hertfordshire. Three glauconitized and phosphatized hardgrounds known as the "Reed Facies" in a single degraded face in the Reed RIGS site. |
| Reference(s): |
| Hopson, P M, Aldiss, D T and Smith, A. 1996. The geology of the country around Hitchin. Memoir of the British Geological Survey, Sheet 221 (England and Wales). |
| Shepard-Thorn, E R, Moorlock, B S P, Cox, B M, Allsop, J M and Wood, C J. 1994. Geology of the country around Leighton Buzzard. Memoir of the British Geological Survey, Sheet 220 (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
