Geoscience Reference
In-Depth Information
N
Blockfield
Riegel
Rockwalls
To r s
Moraine
Lake
Major glacial
breach
Minor glacial
breach
Protulus
rampart
Infilled lake
Quarry and
quarry spoil
Till
3
Thick scree
or head
Debris fan
L.Marchlyn Bach
4
L.Marchlyn
Mawr
1
5
Y Galan
2
6
7
400m
L. Ogwen
Ogwen
Step
Y Llymllwyd
Pen y Benglog
8
Pont Rhyd-Goch
L. Idwal
L. Clydr
Cirque names
9
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Marchlyn Bach
Marchlyn Mawr
Ceunant
Graianog
Perfedd
Bual
Côch
Cywion
Cl ˆd
Idwal
Cneifion
Bochlwyd
Tryfan
Gwern gof
y Gors
L. Bochlwyd
Gallt yr Ogof
10
15
Tw l l Du
13
14
14
11
L. Caseg-y-
fraith
Casell y Gwynt
0
1
km
Source: Addison (1987)
c.
11,500 yr
BP
. Boulders on outer and inner moraines in
Cwm Idwal have yielded
36
Cl ages of 12,900 ± 2000
BP
and
11,600 ± 1300
BP
respectively (Bowen 1989), the latter
regarded as age-equivalent to GS-1.
Palaeosols generally are of two types, both of which occur
here.
Relict palaeosols
on the present land surface were
formed under a different environment in the past, whereas
buried palaeosols
, also called
fossil soils
, are preserved
beneath younger sediment. The high western and central
moors were ice-free during the Devensian glaciation, and
have weathered, base-poor relict laterite soils formed
during the last interglacial stage (MOI 5e). Soil formed
under a tropical seasonal climate, with mean temperatures
5
Palaeoecological evidence of climate and
landscape change in upland Britain:
North York Moors
C above those of today; in the wet season intense
leaching gives pallid, almost white horizons, whilst
dehydration in the dry season allows prominent red
iron mottles to form (
Plate 23.14
)
(see
Chapter 18).
Fossil
palaeosols are also found on the moors as brown soils
Regional context
The North York Moors landscape has undergone many
changes over time, and evidence for changes of climate,
soils, and vegetation is preserved in palaeosols, peat bogs,
archaeological sites and occasional lakes (
Figure 23.15
).
