Open Journal of Geology, 2020, 10, 612-640 https://www.scirp.org/journal/ojg ISSN Online: 2161-7589 ISSN Print: 2161-7570 Landforms Evolution of Wadi Qudaid Area, West Central Arabian Shield, Saudi Arabia: An Example of the Role of the Geological Factors in the Urban Extensions Ali A. Mesaed1,2, Mohammed A. M. Alghamdi3, Abdullah R. Sonbul3 1Geo-Exploration Techniques Department, Faculty of Earth Sciences, King Abdulaziz University, Jeddah, KSA 2Geology Department, Faculty of Sciences, Cairo University, Giza, Egypt 3Engineering and Environmental Geology Department, Faculty of Earth Sciences, King Abdulaziz University, Jeddah, KSA How to cite this paper: Mesaed, A.A., Abstract Alghamdi, M.A.M. and Sonbul, A.R. (2020) Landforms Evolution of Wadi Qudaid Area, Wadi Qudaid is located in the west central part of Saudi Arabia. It about 135 West Central Arabian Shield, Saudi Arabia: km to the northeast of Jeddah city along Al Haramein highway and it An Example of the Role of the Geological represents the upstream of the very large alluvial plain along the Red Sea Factors in the Urban Extensions. Open Jour- coast. It runs in NE direction parallel to many wadis of the west central part nal of Geology, 10, 612-640. https://doi.org/10.4236/ojg.2020.106028 of Saudi Arabia i.e. Wadi Fatima, wadi Sitarah. The wadi floor is filled by Qu- aternary deposits which represent good groundwater aquifer. Geologically, Received: May 12, 2020 the present-day residual landforms of Wadi Qudaid are composed mainly of Accepted: June 13, 2020 Precambrian Arabia shield rocks overlained by Tertiary sedimentary rocks Published: June 16, 2020 and finally harrat (Tertiary volcanic). The Precambrian rocks are represented Copyright © 2020 by author(s) and by 1) a lower layered basic and intermediate volcanic and the intercalated Scientific Research Publishing Inc. volcaniclastics. This unit is correlatable with Samran Group, 2) an upper This work is licensed under the Creative layered acidic volcanic and the intercalated acidic volcaniclastics. The Ara- Commons Attribution International License (CC BY 4.0). bian shield rocks are intensively folded and dragged along the major NE http://creativecommons.org/licenses/by/4.0/ faults. They are directly overlain by Tertiary basic volcanic (harrat) and the Open Access related volcanoclastic red beds). The main geomorphologic elements of the study area include plateau, scarps, and the wadi floor. The plateau is represented by the black basaltic sheet that contains some semi-rounded depressions filled with Quaternary eolian sands. The scarps of the main wadi and its tributaries are nearly steep and contain many asphaltic roads with some isolated cone hills detached from the scarps. Geomorphological, Wadi Qudaid represents the incomplete erosion cycle that begins with the formation of deep galleries and very steep and narrow wadies formed along the major NE faults and re- lated fractures and folds. The progress of the erosion processes led to the for- mation of narrow interfluves as a result of pedimentation and sculpturing of DOI: 10.4236/ojg.2020.106028 Jun. 16, 2020 612 Open Journal of Geology A. A. Mesaed et al. the wadies sides by scarp retreat. The peniplanation stages of the erosion cycles are reached in the southwestern and the central part of the wadi where fast pe- niplained areas were formed. The results of this study revealed the role of the different geological processes (lithology, structural elements and climatic con- ditions) in the distribution of present-day human populations in urban exten- sions. Qudaid, Dhubaya-Jumah, Dabyah, Al Khamrah, Almansa and Al Mas- samah are the main villages of Wadi Qudaid area. Keywords Wadi Qudaid, Geomorphology of Saudi Arabia, Landforms Evolution, Erosion Cycle, Urban Extensions 1. Introduction 1.1. Literature Review Wadi Qudaid is occupied by many villages and contains a lot of green private farms. The present-day human population of Wadi Qudaid area depends on the private and governmental wells. The area is of good climate in the winter, but it is very hot in the summer periods. The geomorphology, hydrology and drainage morphometry of Jeddah-Makkah district appears in the publications [1]-[8]. The climate of Jeddah Governate is a hot arid desert type, with some rainfalls in the spring season; the temperature reaches a maximum of 49˚C within the period between March and August, and a minimum of 17.3˚C during the period be- tween January and February. The groundwater of Wadi Qudaid area is suitable for agriculture purposes and the results of the chemical analyses show the nor- mal content of Ca, Mg, Na, Cl, SO4, and HCO3 [9]. They also concluded that the groundwater aquifer of the northeastern part has shallower depths than in the southern part and the Quaternary deposits are thinner in the northeastern part than the southern part (downstream). The study also revealed that the ground- water is of good quality in the upstream (NE) area than the downstream (SW). 1.2. Aims of the Study This present study aims to give a detailed description of the different landforms of Wadi Qudaid area. Also, the study deals with the clarification of the different geomorphologic processes that resulted in the formation and evolution of the landforms of the study area. The second aim of this study is to clarify the role of the different geological factors in the human populations and urban extensions in the study area. 1.3. Methods of the Study This study is based on detailed field measurements and descriptions of the dif- ferent landforms. Global mapper and Arc GIS programs are used in the prepara- tion of the satellite images and geologic maps as well as the topographic and DOI: 10.4236/ojg.2020.106028 613 Open Journal of Geology A. A. Mesaed et al. contour maps. The results of the study are combined together with drawing dif- ferent geomorphologic models illustrating the landforms’ evolutional history. 1.4. Geologic Setting The study area is of characteristic geologic and geomorphologic setting. It represents a part of the Arabia shield rocks of the west central part of Saudi Ara- bia (Figure 1). It contains many NE trending wadies i.e. wadi Fatima, Wadi Qudaid, and wadi Sitarah. Wadi Ashamiyah and wadi Ashumaysi are NW trend- ing (Figure 1). The geology of Makkah area is described by [10] to include older basement rocks which overlay, by the sedimentary rocks, then the volcanic rocks Figure 1. Mr. Said satellite image of Makkah districts showing the general physiography and drainage lines and the location of Wadi Qudaid. DOI: 10.4236/ojg.2020.106028 614 Open Journal of Geology A. A. Mesaed et al. (basalt 2 older and basalt, younger) and finally the Quaternary deposits which are subdivided into five types (Figure 2). According to the Arabian shield map [11], the study area comprises four main geologic units: 1) The Arabian shield rock units which are composed for igneous and metamorphic rocks (Figure 3); 2) Tertiary sedimentary succession which is present just underlying the Precam- brian Arabian shield rocks which are presented by slope-forming unit of inter- calations of clays, sandstones, siltstones and sandstones; 3) Tertiary harrat which consists mainly from basic volcanic of basalt, dolerite amygdaloidal and vesicu- lar basalts. This unit forms the uppermost black horizontal sheet on the submit of most of landforms, and 4) Quaternary wadi deposits which form the floor of Wadi Qudaid and the small tributaries of Wadi Qudaid (Figure 1). These depo- sits are composed mainly of gravels, sands, silts and clays. The groundwater of the study area is mainly recorded within these deposits. Figure 2. Geologic map of Makkah districts showing the different rock units [10]. DOI: 10.4236/ojg.2020.106028 615 Open Journal of Geology A. A. Mesaed et al. Figure 3. Geologic map of Makkah districts showing the different rock units and the main asphaltic roads [11]. The Arabian shield rocks are present in two subunits: 1) lower metamor- phosed basic volcanic and the intercalated volcaniclastics (Figure 4(A)). This unit is present in the southern part of Wadi Qudaid and, 2) Acidic volcanic and the intercalated marble deposits which are present in the central and northern (upstream) part of Wadi Qudaid. It overlies the green schist and amphibolites of the above-mentioned unit and underlies the Tertiary volcanics (harrat) or Ter- DOI: 10.4236/ojg.2020.106028 616 Open Journal of Geology A. A. Mesaed et al. tiary sedimentary succession of Usfan Formation (Figure 4(B), Figure 4(C)). This unit is composed of interbedded rhyolite, rhyolitic tuffs, chert, and quartz bands (Figure 4(C)). Thin black basic bands are present within the middle and upper part of the succession (Figure 5(A)). White color carbonates and/or quartz bands are also present (Figure 5(A)). The Tertiary sedimentary succes- sion is composed of volcaniclastic red beds, sandstones, siltstones, basalts, and carbonates (Figure 5(B)). This unit is of characteristic color and it is excavated Figure 4. (A) The black metamorphosed rocks (green schists and amphibolites) of Samaran Group (basic volcanic and the associated volcaniclastics of unit 1); (B) Unit 2: acidic volcanic and the associated volcaniclastics of unit 2 (lower light color part of the photo) and the overlying black basalt (harrat) (upper part of the photo); (C) Folded acidic volcanic and the associated volcaniclastic of unit 2. DOI: 10.4236/ojg.2020.106028 617 Open Journal of Geology A. A. Mesaed et al. Figure 5. (A) The black ad light zones of the acidic volcanic and the associated volcaniclastics unit 2, the northern part of Wadi Qudaid; (B) Volcaniclastic red beds of the Tertiary sedimentary succession just underlying the basalt (Harrat); (C) Alluvial fan conglomerates of the wadi fill deposits of Wadi Qudaid.