On 02/02/2014 23:22, Joe Egginton wrote:
A 30ft sinkhole has swallowed a car in High Wycombe, from the photos
there's no water at the bottom so it can't be an underground stream. I
don't think there's any mines around there. So what caused the sink hole?

http://www.bbc.co.uk/news/uk-england...herts-26010192


2.1
Location, Topography & Geology

High Wycombe lies within the Wycombe District in the southern half of
the County of Buckinghamshire. The modern parish of Wycombe comprises
the old borough of Chepping Wycombe and the rural parish of High
Wycombe. Chepping Wycombe lies in the valley of the River Wye with
modern settlement expanding to the south up the hill into West Wycombe
and Great Marlow parishes and to the north up Amersham Hill as far as
Hazelmere parish. The modern extent of the town also expands east as far
as Wycombe Marsh and west up to West Wycombe village.
Chepping Wycombe is a linear settlement formed along a major road from
Oxford to London where it parallels the path of the River Wye. The
borough lies in the base of the valley floor at a height of
approximately 70m OD (Ordnance Datum). Modern settlement then rises in
the north to a height of 175m OD at the top of Amersham Hill and to a
height of 155m OD at the top of Cressex south of the borough.
The principal bedrock geology of High Wycombe comprises Middle Chalk
formation along the path of the River Wye surrounded by Upper Chalk
formation across the rest of the settlement. The overlying superficial
deposits mainly comprise alluvium along the path of the River Wye and
clay with flints across the tops of the ridges.
The Soils Survey Layer (Cranfield, 2007), surveyed at a county level,
classifies the soil along the path of the river as seasonally wet loam
over gravel (Soil Series 8.12 Calcareous alluvial gley soils). The soils
to the south of the loam as far as Wycombe Abbey is classified as
shallow loam over chalk (Soil Series 3.43 Brown rendzinas) with further
areas of shallow silt over chalk around Sands to the west of the town
and around Amersham Hill to the north (Soil Series 3.43 Brown
rendzinas). Two further bands of deep loam over clay are also projected
around Daws Hill to the south and Totteridge to the north (Soil Series
5.82 Stagnogleyic paleo-argillic brown earths).

http://www.buckscc.gov.uk/media/1305...mbe_report.pdf

Chalk and Portland Limestone under water-logged clay, so anything's
possible.

jim, Northampton